Federal regulation of the trucking industry encourages price fixing, inadequate service and high consumer costs, a study distributed yesterday by the Senate Judiciary Committee concludes.

The report's conclusions are not surprising since the panel's chairman, Sen. Edward M. Kennedy (D-Mass.) is a leading advocate of trucking deregulation, along with President Carter.

The report offers new information about the activities of trucking companies under the regulatory supervision of the Interstate Commerce Commission.

An unnamed trucking firm, in documents obtained by the committee, outlined a scheme of avoiding rate cutting. It is "corporate policy to us as well as to most of our competing common motor carriers to refrain from proposing rate reductions merely to divert freight from one of our lines to the other," an executive of a leading trucking company wrote.

The same company executive said that it would "smack of solicitation through price competition . . . an out and out violation of management philosophy."

The committee could not release the names of the companies because of current litigation over the documents, which remain under a limited protective order.

The committee report cited several examples of corporate unwillingness to challenge the pricing practices of other trucking firms and suggested that such activities could be eliminated only if the antitrust exemption that allows truckers to set rates in rate bureaus were lifted by Congress.

In addition, the committee investigation of trucking practices also revealed that some companies engage in "negative sell," a practice designed to discourage customers from requesting service along unprofitable routes.

A memo from a Consolidated Freightways Corp. manager concluded that the firm is "actively discouraging this freight by informing the customers that, due to service problems, we cannot give them the service they need and deserve in these areas at the time."

The committee concluded that a practice of "traffic selectivity" discourages unwanted freight, but also ignores "requests to handle it."

The 285-page report, which was released for comment before being put into final form, essentially outlines the case that deregulation advocates here been making since the issue began receiving public attention two years ago.

The report represents the findings of the committee, which heard from 93 witnesses during 14 days of hearings.

In addition, the panel conducted its own investigation of the industry's practices and the regulatory system, including analyzing thousands of pages of internal industry documents.

Although the report suggests the ICC has done all it can to monitor the industry, it also concludes the federal laws that govern trucking regulation are outdated and lead to inefficiency.