WASHINGTON (AP) _ Five corporate executives paid an unusual visit to Capitol Hill on Monday to throw their weight behind a cause rarely associated with big business: education programs for disadvantaged children.

''We're all activists,'' said William Woodside, retired chairman of American Can Co. in New York, before testifying at a joint hearing of House and Senate education subcommittees. ''We're here to add some weight and influence in the continuation of programs that have shown some success.''

The high-powered group made a pitch not only for renewal of the federal Chapter 1 program for poor and educationally disadvantaged children, but for greater federal outlays so the program can reach more of its target group. Currently fewer than half those eligible are served.

Self-interest as well as altruism was cited by the senior corporate officers as they explained why they were appealing to Congress on matters other than taxes and mergers.

With one-third of the nation's children expected to be poor by the year 2000, they said, failure to invest in their education could have serious consequences for national defense and international competitiveness.

However, the executives differed on where to find the additional dollars in view of the federal deficit.

''I find the Department of Defense a great unexploited gold mine for finding additional funds for social programs,'' Woodside said, adding he is not opposed to higher taxes or deferred tax cuts either.

Charles W. Parry, chairman of the Aluminum Co. of America based in Pittsburgh, told committee members that deficit reduction is imperative. If they can't make the tough political choices and fund education, he said, higher taxes are the only answer.

Earlier, Gerald D. Foster, region vice president of Pacific Telesis Group in Los Angeles, said lawmakers should look to the corrections system. ''We're spending $18,000 a year to keep a (high school) dropout in jail,'' he said, contending the money would be better used preventively in the early grades.

The executives said they would opt for Chapter 1, which offers remedial classes and other help to children mostly in the early grades, when asked by a committee member what they would do if forced to choose between it and worker retraining.

''A lot of these people will never get an opportunity to be retrained if we ignore Chapter 1... We've really got to do both,'' said Foster.

''I would cast my vote in favor of the younger generation,'' Woodside said. ''That's where the long-term impact of the system is going to be. The other is a somewhat finger-in-the-dike situation.''

At a breakfast before the hearing, the executives described their hiring problems and efforts to form partnerships with local school systems.

''They can't read, they can't write, they can't make logical deductions from a set of facts, they can't do math,'' Woodside said when asked about the shortcomings of job applicants.

''I don't see a substantial or dramatic deterioration. But ... the nature of the jobs is changing,'' said William Edgerly, chairman of State Street Bank and Trust Co. of Boston.

The business executives said they are trying to work more closely with schools, offering students courses, summer jobs and scholarships. They also said they have restructured their corporate contribution programs to permit and encourage donations to elementary and secondary schools.

But they stressed that they have neither the resources nor the expertise to educate the work force.

''I definitely do not think that education is a private affair,'' Woodside said. ''There's no way the private business community can replace public funding and solve the problems facing the education world.''

Among the problems they mentioned: inadequate teaching of basic skills, students failing to develop work habits such as punctuality, a dropout syndrome that seems to be spreading among families and groups of families, an exodus of retiring teachers whose successors are not as well qualified, and an influx of minority and refugee students who tend to be poorer and in worse health than others.

The Chapter 1 program for low-income and educationally disadvantaged students currently receives $3.9 billion in federal money and serves about 5 million students. While federal support has fallen in the past few years, the Reagan administration has proposed a $200 million increase next year. However, the money is expected to cover inflation without expanding the program.

Also appearing Monday with Woodside, Parry, Edgerly and Foster was Charles Marshall, vice chairman of American Telephone & Telegraph Co. in New York.