Responding to complaints that the Carter administration is focusing too much attention on big cities, Patricia Roberts Harris announced yesterday that she has ordered a study of the needs of small-town and rural America.

Harris, secretary of Housing and Urban Development, said in a speech to the Washington Press Club that she has appointed a task force to see if housing and community development funds to small localities are adequate.

Noting that last year HUD assumed the revitilization of cities as a major responsibility, she said the task force would now "focus some well deserved attention on the needs of rural areas."

The task force review stems in part from a congressional directive last year calling upon HUD to study the housing and community development needs of cities under 50,000 population.

It also results from complaints HUD officials received at a convention of the National League of Cities early last month that they were not addressing the problems of small-town America.

"We're delighted to see that HUD has responded," said Alan Beals, executive director of the league, which represents elected officials of 15,000 cities of all sizes.

"Smaller cities have problems and concerns similar to those of large cities," he said. "There's outward migration in some. There's growth in others that's outpacing available water and sewer lines. Some have substandard development, like trailer camps. Some have depressed economies because of new regional shopping centers. Many lack adequate planning."

HUD funds are available to communities with fewer than 50,000 people through discretionary grants. Most larger cities get HUD money automatically, but small towns outside metropolitan areas often must compete among themselves for the funds. About a quarter of HUD's community development and assisted housing money goes to such communities.

An Agriculture Department study last year showed that in 1975 localities outside metropolitan areas got $91 per capita in federal community development funds while those inside such areas got $80 per capita.

"The distribution now is probably in balance," said a congressional staffer, "but obviously small-town officials feel that they will receive less money as the administration moves toward an urban policy."

Harris said the task force will also study whether small communities with limited resources are spending too much money and going through too much red tape to get HUD community development grants.

The task force will compare HUD's programs for small towns with those of the Farmers Home Administration to see if duplication can be eliminated. Both agencies have housing, planning, and community development programs.

Harris said the study group will look at new ways to provide housing services to rural areas and will try to help them get better planning advice.

The task force will be headed by Joseph Burstein, who is counselor to Harris. A. Russell Marane, HUD's administrator for the Atlanta region, will be vice chairman.

Harris said that by "studying the problems of rural areas while at the same time revitalizing our cities, we are contributing significantly" to people's freedom to choose where they want to live.

"In the past we have tended to skew the conditions that lead people to make choices in the direction of our suburban areas," she said.

Harris said the task force will make its recommendations to her by March 1.