The Joint Economic Committee yesterday criticized the Interstate Commerce Commission under Chairman Reese Taylor, an appointee of President Reagan, for failing to carry out the congressional mandate to deregulate the trucking industry.

"It is the committee's conclusion that the ICC under Chairman Taylor has abandoned the goal of a freely competitive trucking market and has moved to reverse the progress toward deregulation which has recently been made," a committee report charged.

A spokesman for the ICC said yesterday that Taylor rejects the committee's conclusion that the ICC has moved to reverse the progress toward deregulation. "He believes the ICC has been moving at a steady pace to implement and administer the reforms envisioned by Congress in passing the Motor Carrier Act of 1980," the spokesman said.

The report, signed by 15 of the committee's 20 House and Senate members--eight Democrats and seven Republicans--said current ICC policies contradict the intent of Congress and are at odds with President Reagan's campaign promises and his administration's stated pro-deregulation philosophy.

The committee called on the president to "offer immediate public guidance" to the ICC on the subject of trucking deregulation, and to create a pro-competitive majority on the commission.

In "additional views," five of the Republicans who signed the report said they support the goal of deregulation but thought the report's criticism of Taylor was "too harsh." They said they believed there was merit to Taylor's contention that the law does not allow him totally to deregulate the trucking industry.

In its report, the committee contended that the ICC under Taylor had begun to backpedal from the pro-competition decisions of the deregulation-minded agency led by President Carter's appointees. As a result, the report contends, there is now more regulation. To support the charges they said that:

* Grants of operating authority to trucking firms have been more narrow than requested, often restricted to certain territories and commodities named by supporting shippers who said they would use the service. Before, the agency took the shippers' support to indicate a broad potential demand that could justify the requested authority.

* Costly, time-consuming oral hearings are being required more frequently than before, discouraging some truckers who might otherwise seek new or expanded authority.

* Rate reduction filings are being reviewed more closely than before on the commission's initiative to make sure they are not "predatory or discriminatory," even if no one has filed a complaint.

In the JEC hearings that led to the report, Taylor said his actions at the commission are in keeping with the law and that the preceding commission had gone too far toward deregulation. In that regard, he cited a recent court decision that held that some ICC regulations were too broad to be consistent with the law. The court had ruled that new ICC rules for classifying commodities would have had the effect of giving some grants of authority broader even than requested by the trucking firm. The committee yesterday charged that Taylor voted against appealing the decision to a higher court.

The report noted that Taylor has stated his intention to seek congressional approval for a new standard for entry to the trucking industry: the elimination of current "public convenience and necessity" guidelines with emphasis solely on a showing that an applicant is "fit, willing and able" to provide the service for which authority was sought.

Although Taylor says the new standard isn't meant to be restrictive, the report contends it could be far more restrictive than current law. It could be construed, for instance, to require a firm to show that it already has a large fleet of trucks to prove that it is "able" if it is seeking nationwide authority. "

Taylor also has said he plans to appoint a task force to study ICC jurisdiction over motor and rail operations to determine whether the agency can divest itself of some jurisdiction where ICC regulation isn't needed anymore.