The massive and widely celebrated post-Watergate "reforms" in federal elections laws have given the country five years of overregulated, underfunded political campaigns even more dependent on special interest money than they were before, according to a Harvard study commissioned by a House committee.

The laws have further diminished the role of the major political parties in campaigns, the study said, while at the same time having a chilling effect on minor candidates throughout the country.

The House Administration Committee now is considering the study's recommendations, which include a heavy dose of deregulation and a tripling of the current $1,000 limit on individual contributions to one campaign.

The study is the first congressionally commissioned review of the laws, which were totally in place for the 1976 congressional and presidential races. Designed to "restore confidence" in the integrity of the elections system, the revisions were intended to eliminate the individual "fat cat" contributor with stringent contribution limits, and they required complete public reporting of all receipts and expenditures.

The study says publicly what many politicians have been saying privately: that in many respects, the law simply has not worked and in other respects has produced results opposite those intended.

The most striking failure has been the increased role of special interest money, according to the Harvard Institute of Politics Campaign Finance Study Group, which produced the report.

The $1,000 limit on individual contributions, combined with the skyrocketing costs of campaigning, has so squeezed candidates that they have relied even more on corporate and labor political action committees. The percentage of money raised by congressional candidates from PACs - as these fund-raising committees are called - has doubled since 1972 to about 25 percent in the 1978 elections. The PACs, in turn, raised about $75 million in 1977 and 1978 to influence federal elections.

These PACs can contribute $5,000, not $1,000, to a single candidate. They are highly organized and centralized as well, thus making PAC money more easily obtainable for a candidate than the high-overhead solicitations and dinners used to raise money from individuals.

"The money flowing through PACs is increasing far more dramatically than is the total amount of money raised by congressional candidates," the study said.

"PACs have increasingly supplanted other sources of money in politics and candidates for Congress have become increasingly dependent" on them, the study said. "If one of the original intentions of campaign finance reforms was to limit the appearance of special interests in the political process, the law has, in practice, had the opposite effect."

Fund raising, the study said, has been increasingly "nationalized" in these Washington-based PACs, with a concomitant decline in grass-roots fund raising in home districts.

There has been an equally dramatic increase in the use of a candidate's personal resources in campaigns, making it all the more difficult for average-income people to even contemplate running for federal office, the study said.

The law also restricted the contributions of political parties to a candidate to $5,000.This has caused a "further deterioration of their roles. In 1972, the study said, about 17 percent of the money for congressional candidates came from their parties. In 1978, the figure was down to about 4.5 percent.

The House Administration Committee, which oversees the law's implementation, will steer clear of any changes in the contribution ceilings, according to chief counsel Bob Moss, until possibly next fall.

Agreement has been reached on reducing the burden of regulation under the Federal Election Commission, he said, and Congress will consider in the next few weeks a dramatic reduction in the paperwork required of candidates.

The paperwork - the detailed reports of every expenditure and every contribution of $100 or more - has increased the costs of a campaign and placed a special burden on "local party committees, smaller campaigns, new entrants to the political system and candidates from outside the two major parties."

The study recommends a sharp reduction in what must be reported and total exemption from detailed reporting for candidates who raise less than $5000.