BRUSSELS, Belgium (AP) _ The Reagan administration's plans for a small increase in military spending may hurt efforts to get European allies to pay a greater share of the common defense, analysts say.

''This will create some tensions,'' said Hans Binnendijk, director of studies for the London-based International Institute for Strategic Studies.

Defense Secretary Frank Carlucci asked Congress to boost defense spending by an inflation-adjusted 2 percent for the next two years in the draft military budget. He proposed $315.2 billion in budget authority for 1990, and $330.89 billion for 1991.

The spending plans, however, will likely be modified after George Bush assumes the presidency.

There has been growing criticism in the U.S. Congress in recent years that America's allies in the North Atlantic Treaty Organization are not shouldering enough of the burden of financing a common defense. NATO defense ministers in December released a report on the ''burden-sharing'' issue and faulted some in the 16-nation Western alliance for not doing enough.

In the late 1970s, the United States began pressing for an inflation- adjusted 3 percent annual increase in each country's defense spending, a sum that has become a rough guideline for measuring military expenditures.

Martin McCusker, director of the military committee of the North Atlantic Assembly, said the draft budget plan ''will certainly blunt the argument that some will make now - that some Europeans are not even keeping up with the minimum 3 percent.''

''It will show the United States is not reaching that level either,'' he said. The assembly is made up of legislators who represent the NATO countries.

A spokesman for the U.S. mission to NATO said, ''Budgetary constraints have required the proposal for only a 2 percent increase.''

''Given the long-standing burden-sharing issue, the United States would nonetheless hope that those countries which have not met past goals would not use this as an excuse for lowering their budget projections,'' said the spokesman, who demanded anonymity.

The NATO report on burden-sharing said that on average in the past decade, Canada, Italy, Luxembourg, Norway, Spain, Turkey, Britain and the United States generally met the 3 percent goal.

Belgium, Denmark, Germany and Greece posted the smallest average growth levels, it said.

''Although some countries have improved performance in the last five years (Canada, Greece, Italy, Netherlands, Norway, Turkey and the United States), performance in general has been somewhat less successful and this downward trend generally seems set to continue,'' it said.

Binnendijk said that although Carlucci wants a 2 percent pickup in military spending, ''the reality is they are not going to get any real increase.''

''Because of the budget constraints on Capitol Hill ... the best the Pentagon can hope for is a straight line in real terms. Growth of 2 percent is highly unlikely,'' he said.

Indeed, Congress has trimmed the Pentagon's wish list in recent years.

It approved a 1.3 percent inflation-adjusted decrease in budget authority in the current 1989 fiscal year, which ends Sept. 30. The administration had presented a budget proposal of $299.5 billion under a compromise money plan worked out with Congress. That proposed spending level was not large enough to offset inflation.

Congressionally approved budget authority was off 2 percent in 1988, 3.7 percent in 1987 and 4.4 percent in 1986. It soared 7.6 percent in 1985, which had marked the sixth straight year of increases.

NATO's European members have responded to the U.S. push for more military money with figures showing their total defense spending skyrocketed 34 percent, after adjustment for inflation, between 1970 and 1987. U.S. spending, in contrast, was up 15 percent over the same period.

Per capital defense spending, according to these figures, grew 21 percent in the European countries over the 1970-86 period, compared with a 3 percent decline in the United States. Military manpower advanced 5 percent in Europe over 1970-87, compared with a 31 percent decline in the United States, according to the European figures.