Three congressional critics of President Reagan's Central America policies have charged that most of the $1.7 billion in U.S. aid provided to El Salvador during the past five years has been used to pursue a military solution to the Salvadoran civil war rather than for "economic and social development" as the administration claims.

The administration has used "insufficient, misleading and in some cases false information" to disguise the fact that only 15 percent of U.S. aid has been used for "reform and development," the three legislators claim. The critics assert that the rest has been direct military aid or war-related aid applied to "a step-by-step escalation of a strategy for a military victory."

The charges are contained in a report to be released today by Sen. Mark O. Hatfield (R-Ore.), Rep. Jim Leach (R-Iowa) and Rep. George Miller (D-Calif.) to the congressional Arms Control and Foreign Policy Caucus, a 130-member bipartisan group.

It was distributed to members of the caucus yesterday but was prepared by the three lawmakers and their aides and does not seek to reflect the views of the membership, the report says. Hatfield, chairman of the Senate Appropriations Committee, is a former caucus chairman; Leach is the present chairman, and Miller is chairman of its El Salvador task force.

The report challenges administration assertions that it consistently has allocated aid to Salvadoran economic and social development rather than to military activities "by a 3-to-1 margin." The report says analysis shows this claim to be "flawed because it describes aid simply by which U.S. agency administers it -- rather than what the aid is actually used for."

The report describes "indirect, war-related aid" as including cash transfers to sustain the Salvadoran government and economy in the face of war-induced economic collapse, aid to persons displaced by fighting and rebuilding of infrastructure damaged by leftist guerrilla activity. Over the last five years, the report contends, this type of aid has accounted for $767 million or 44 percent of the total U.S. program.

The report says another $523 million, or 30 percent of overall aid, was devoted to direct, war-related assistance such as expanding, training and equipping the Salvadoran armed forces. Only $267 million went to genuine development work such as reform of agriculture and the judiciary.

According to the report, the ways in which aid have been applied show a "low priority" for reform. "Our original attempt to expand and upgrade the Salvadoran army has broadened . . . , resulting in a counterinsurgency strategy, reminiscent of Vietnam . . . , which has heightened the casualties among the civilian population," it says.

The report also cites as examples of the administration giving false or misleading information to Congress:

* Failing to inform all relevant congressional committees of plans to build an air base in eastern El Salvador until after Congress had voted on Salvadoran aid requests.

* Hiding from "virtually all members of Congress" plans to supply El Salvador with four AC47 gunships and then downgrading the plan to one gunship after Congress learned about the original four-plane plan through press disclosures.

* Asking for $93 million in supplemental military aid for El Salvador two years ago on the grounds that "a dire emergency existed in the supplies available to the Salvadoran army, when, in fact, the Pentagon's own management data show that this claim was false."