Despite sporadic assaults from some members of Congress and officials of the Reagan administration, the political reforms that grew out of the Watergate scandals of the 1970s remain largely intact.

There have been attempts to diminish the broadening amendments tacked onto the Freedom of Information Act in 1974. There have also been efforts to modify campaign financing restrictions put in place in that era, and to water down financial disclosure requirements imposed then on legislators and government executives.

But the reforms' promoters, while wary, believe most of the changes have survived and are effective.

Archibald Cox, who played a central role in the Watergate investigation and was fired from the special prosecutor's job by then-president Nixon, said yesterday, "The administration has been insensitive to the concern for ethics in government."

"I hear calls for repeal of the special prosecutor's office and a weakening of the Office of Ethics and the financial disclosures," said Cox, now chairman of Common Cause, the self-styled citizens' lobby.

The Watergate scandals produced a wave of reforms designed to control the political influence of special interests, diminish official secrecy, check the power of the executive branch and institutionalize the prosecution of official corruption.

Revelations of large contributions from corporate groups to Nixon's 1972 campaign fund spurred Congress to enact in 1974 a public finance law for presidential elections. Reformers believe it has worked well, but they note that part of that law opened the door for massive special-interest donations to congressional campaigns through political action committees, or PACs.

There were 589 PACs in 1974. Now there are more than 3,000. Common Cause estimates that by the 1984 elections they will contribute more than $100 million to congressional candidates.

Cox said yesterday Congress must either put a ceiling on PAC contributions or enact a public financing law for its own elections.

Congress in 1978 enacted ethics codes to govern both houses, limiting the amounts of gifts and speaking honoraria that members can receive. But the Senate has repealed the $25,000 annual ceiling on honoraria.

Wholesale efforts to decimate the campaign finance law and emasculate the Federal Election Commission, which oversees compliance, have failed, although the commission is still widely unpopular in Congress. It has been forced to obtain operating funds under a continuing resolution, without a new appropriation, for two years.

Some Senate Republicans, with Reagan administration support, also attempted to water down the 1974 amendments that strengthened the 1966 Freedom of Information Act. Strong opposition from the news media and other groups blocked the more far-reaching changes and a compromise bill making modest alterations has emerged from the Senate Judiciary Committee.

But administration critics contend that a presidential order issued in April will lead to extensive secrecy in many cases.

The order, said Sen. Patrick J. Leahy (D-Vt.), "goes back to the old idea that if we make enough things secret we can do all we want. There are some people down there in the executive branch who want to classify everything. What will happen is that mistakes and fraud and cost overruns will all become classified."

A law requiring full public disclosure of the financial holdings of congressmen and top executive branch officials has survived sporadic criticism, and last year more than 11,000 disclosures were filed. But recent comments from high Reagan administration officials indicate an intent to recast the law on grounds that it discourages many persons from public service.

The Budget and Impoundment Control Act of 1974 was also in its way a product of the Watergate era, an attempt to reassert congressional authority over spending, in part provoked by Nixon's legally questionable practice of impounding, or refusing to spend, money appropriated by Congress.

But the law permits the executive branch to rescind or defer some spending items if Congress concurs, and some critics in Congress contend the Reagan administration has skirted the law.

In a recent letter to House colleagues, Rep. Norman Y. Mineta (D-Calif.) accused the executive branch of "failure to report impoundments, reprogramming of funds without congressional action, misclassification of impoundments, and withholding funds late in the fiscal year so that they lapse . . . ."