Growing state reforms of public school financing, heralded as a way to equalize spending for rich and poor students, apparently have done little to accomplish this aim.

The financial imbalances that led to the movement for change seem to persist, even though the reform states are spending more on schools, according to a new study by the Rand Corp. of Santa Monica, Calif.

Ironically, researchers Stephen J. Carroll and Rolla Edward Park reported, the property tax dispartities are fewer, but the results are the same - the poorer schools remain with the short end of the spending stick.

And, they found, some of the poorer districts may be worse off than before: their per-pupil spending still lags behind the wealthier districts, but their taxes have increased.

The Rand study, financed in part by the federal National Institute of Education, concentrated on five states that have altered their school-financing systems - California, Florida, Kansas, Michigan and New Mexico.

Its findings seem destined to add more fuel to the nationwide debate over school financing. Reformers, most notably in New York, where they won a major court ruling last year, have contended increasingly that tax changes also must assure that classroom dispartities are erased.

This argument holds that state constitutional provisions for equal educational opportunity mean that poorer districts may need more money than wealthier ones.

Generally, Carroll and Park found, the so-called reforms "have not dramatically reversed, or even shifted, the relationships that originally gave rise to reform efforts."

They said that of the five states studied, only New Mexico and California have substantially improved the distribution of revenues to school districts.

"The other states have changed the rules whereby districts raise local revenues and receive state general aid, but they have not much changed the consequences," they wrote

"Regardless of what these states sought to accomplish, their reform plans wrought little change in the distribution of per-pupil revenues . . . In each of these states, the districts that had relatively high revenues before reform have high revenues after reform."

Such imbalances led to the 1971 California Supreme Court Serrano decision, striking down the traditional propety-tax school-financing system, and touched off the nation-wide movement.

The Serrano thesis - that the system discriminated against children in districts with low property wealth - brought about school financing changes in at least 22 states. In virtually every case, the states took over large shares of education expenses.

Carroll and Park said that reforms have "substantially loosened" school revenue ties to local property taxes. And, they said, much of the fiscal advantage held by high-wealth districts was eliminated by the changes.

But at that point the thrust of reform - equalizing educational opportunity - was blunted, they said.

"Poor children, or, more accurately, districts serving disproportionate numbers of poor children, have not fared well in the wake of reform," they wrote.

By and large, they wrote, poor districts had about the same school revenues and lower school tax rates compared with those of higher-income districts before reform as they had after reform.

"Reform has not much affected the distribution of revenues between poor children and rich children, whole the tax rates levied by disproportionately poor districts increased relative to those levied by districts serving higher-income populations, they wrote.

The Rand researchers offered two possible explanations why the reforms in the five studied states did so little to equalize spending.

For one thing, the reforms pursued diversed and conflicting objectives - trying to preserve local controls, avoiding excessive growth in state spending, dodging the political perils of cutting back on high-spending districts.

For another, they said, after the states had drastically altered their school-financing procedures, they then assured continued differences between districts by making "add-ons" and adjustments that tended to favor the wealthier districts.

"For example, Kansas' income tax rebates are disequalizing, as is Florida's cost-of-living adjustment. However appropriate such provisions may be for the needs of a particular state, they make it harder to meet the goals of revenue equalization in school finance," they wrote.

The novel Michigan approach of providing block grants and matching grants to local districts, the researchers found, had little impact on local spending.

The result there, as elsewhere, was that districts that had more money per pupil before reform remained ahead after reform, even though property tax rates for schools dropped in all the states except Michigan.

The Rand researchers chose the five states for study because their new financing laws represented the major approaches to change in the post-Serrano era.