The Federal Aviation Administration announced yesterday that it will proceed with its $1.3 million study for modernizing National Airport, a controversial project that Secretary of Transportation Drew Lewis delayed last fall.

The 18-month study, expected to call for improved and probably larger passenger terminals, an expanded road system and a better connection to Metro, was criticized by Rep. Frank R. Wolf (R-Va.) for "not solving the problem of overcrowding at National and underutilization of Dulles" International Airport.

The study, postponed in September at the urging of Wolf and community groups, will not consider any expansion of National beyond a level the FAA approved in 1981. The FAA owns and operates both National and Dulles.

That 1981 policy slightly reduced the number of commercial jets allowed to use National but permits passenger volume to increase to 16 milllion a year, from 14-15 million in 1979 and 1980, primarily through use of larger airplanes.

Wolf said yesterday he opposes the new study because it will send "the wrong signal to airlines, the community and the citizens who have worked to cap growth at National." He urged the FAA to reduce the passenger cap to between 14 and 15 million. Passenger volumes at National were down in 1982, under 14 million, due at least partly to the air controllers strike and the economy.

A spokesman for Lewis--who leaves office Tuesday--said last night that the study was delayed last fall to allow a companion study of Dulles to begin. That study is almost 80 percent complete and will recommend expansion and improvements there.

Lewis held up the study of National because he didn't want to appear to be giving it precedence over Dulles, the spokesman said. Lewis' designated successor, Elizabeth H. Dole, is appearing before Senate committees this week prior to a confirmation vote.

The new National study is separate from the airport safety study ordered last fall by the National Transportation Safety Board for a half dozen airports. National was included in the study because of safety issues raised after the crash of Air Florida Flight 90, which hit the 14th Street bridge after taking off in a snow storm Jan. 13, 1982.

The new National modernization study, to provide a master plan for changes at the airport, assumes continued operation of National, a controversial issue in Washington ever since jets were permitted to use the airport in the mid-1960s.

The National Capital Planning Commission, federal planning agency for the Washington area, has called for closing National in the next 15 years because of the noise and hazards it poses, a position supported by Alexandria, Fairfax County and several other local jurisdictions but opposed by officials in Arlington and the District.