ATLANTA (AP) _ Delta Air Lines and American Airlines have announced a partnership in a new global computerized reservations system to put an end to criticism of their own systems.

The two airlines, who currently have the only major single-owner reservations systems, announced Sunday that I.

''We have always maintained that the criticism (of single-airline-owned systems) is unjustified,'' American Chairman Robert L. Crandall said in a statement. ''On the other hand, we would prefer to run our business rather than run a debating contest, and we think this is a good solution for all - our customers, our employees and our critics.''

Computerized reservation systems are used worldwide for reserving airline seats, rental cars and lodging, as well as for other travel services and management information services.

Presently there are five such systems in the United States and six elsewhere around the world.

Under the American-Delta partnership, each will own 50 percent of what Delta Chairman Ronald W. Allen termed ''the world's premier CRS system.'' Other international and domestic airlines will have a chance to buy in.

''Delta's investment in the new partnership will allow it to become a major player in the global marketplace for travel information,'' Allen said in a statement.

Max D. Hopper, American's senior vice president for information services, will be chairman of the partnership. The company will be based in the Dallas- Fort Worth area, home of American and its corprate parent, AMR Corp.

The new company will contract with American's SABRE Computer Services for computing and communications. Atlanta-based Delta, whose DATAS II system is smaller, will pay American $650 million, half this year and half next.