Young black children are reading substantially better than a decade ago but there is a decline in the reading skills of white teen-agers nearing the end of their high school education, according to a federally financed study of reading progress in the 1970s.

The study, by the National Assessment of Educational Progress in Denver, paints a mixed picture containing ample material for public education's defenders and critics alike.

Its findings of strong gains by blacks, minorities and low-income children are already being cited by foes of the Reagan administration's proposed cuts in federal aid to schools serving those groups.

Rep. Carl Perkins (D-Ky.), chairman of the House Education and Labor Committee, said in a statement yesterday that the data suggested federal aid was working well.

"I think it would be exceptionally foolish to cut back on these programs now, when we are seeing some real improvements," he said.

Under a Reagan plan, federal aid channeled to schools serving low-income, minority and handicapped children would be reduced sharply and lumped together in grants to state governments or local school boards. Education Secretary Terrel Bell is scheduled to announce details of the proposal at a news conference this morning.

While the findings released yesterday give a boost to those fighting to save federal aid to elementary schools, the declines in the performance of older students provide grist for critics of the nation's high schools, which are under fire as a result of declining test scores and discipline problems.

Ironically, though, the findings appear to contradict assertions by some parent organizations that more instruction in "the basics" is required to reverse the trend. The major decline in the reading tests of the older students showed up in questions requiring deductions and inferences rather than factual recall.

"The results show us that the basic skills are in place," said Marjorie Farmer, director of reading for the Philadelphia public schools. "It's the use of these skills we need to work on . . . We see a fit between these results and the decline of test scores, and the unemployability of many young people. We know we're not succeeding in making enough of a connection between language and learning."

This view was echoed by Seymour Yesner, director of English in the Brookline, Mass., public schools:

"Much of the 'reading' that is taught and tested, though labeled functional and necessary for 'survival,' often seems irrelevant, mechanistic and dull," he said. "In fact, this emphasis may actually be contributing to an unsought-for end -- disinterest and avoidance of reading and seeking out and reliance on more immediate sources of pleasure like TV."

The National Assessment based its findings on a scientific sampling of 2,500 children representing all children in the nation. The sample was broken down into children aged 9, 13 and 17, and results were compared with comparable tests given in 1975 and 1970. Similar "assessments" of the mathematical and writing progress of children already have been published.

Roy H. Forbes, Natioanal Assessment director, noted that those studies also turned up weaknesses in the ability to reason and think critically.

By far the strongest gains in the latest assessment were registered by black 9-year-olds from the Southeast. In 1970 they answered only 45.1 percent of the reading questions correctly. But in 1980, this had risen to 58.1 percent. This still put them 13.5 percentage points below white 9-year-olds from the Northeast, but the gap narrowed by 8.9 percentage points in the decade.

The sharpest decline was registered by white 17-year-olds from the Northeast, whose reading scores on the National Assessment dropped from 72.7 percent to 70.8 percent in the decade. The heaviest slippage occurred among boys, and "advantaged" youths in urban areas.

But the gains of black 17-year-olds compared with 1970 were also negligible, except for those living in the Southeast. Seventeen-year-old blacks in the Northeast showed no change between 1970 and 1980. And the reading scores of blacks of this age living in the West declined by a point.

According to University of Chicago sociologist James Coleman, this pattern is now established enough to present "a nice empirical puzzle."

Coleman said data gathered independently by the National Institute of Education (which also financed the National Assessment study) shows similar patterns. Coleman said one explanation could be deteriorating school discipline which "becomes more of a problem as children get beyond the elementary years."

The National Assessment panel suggested that increased federal funding, increased access to print and electronic media and teaching and "changes in curricular materials" all could have helped younger children, while larger classes, outside employment had "recreational distractions" could all account for the slight decline in reading ability of older children.

One panelist asserted that "simply maintaining the status quo can be perceived as a gain if one considers the increasing number of cultural diversions that are luring these youngsters away from reading.