President Reagan and Canadian Prime Minister Brian Mulroney will be presented with reports today from their hand-picked representatives that call for the U.S. government and industry to undertake a five-year, $5 billion program to test technology for controlling acid rain, government officials said yesterday.

The report also includes a strong statement describing acid rain as an increasingly serious problem in Canada and the United States, without the caveats offered by the administration in the past that "more research is necessary" into its cause and effects, officials said.

Moreover, the report reflects a concession from Canada in that it does not call for specific and immediate reductions in sulfur emissions, which Canada has long sought. Officials said the technology that would be developed in the proposal would, as a byproduct, reduce the emissions, although the exact amount cannot be predicted. Canada may seek more specific reductions later, officials added.

Mulroney's government, which has urged the United States to take stronger action to fight acid rain, is expected to welcome the report. But at a time when deep cuts are envisioned in U.S. government spending, the $5 billion recommendation could put Reagan in an awkward position. Reagan is expected to give the report a low-key response likely to disappoint Canada.

The report includes joint recommendations from Drew L. Lewis, former U.S. transportation secretary, and William G. Davis, former Ontario premier, who were appointed special envoys on the acid rain problem by Reagan and Mulroney at their Quebec City summit last March.

The proposed $5 billion program would be split evenly between the U.S. government and American industry, according to officials familiar with the report. The report does not specify how industry's $2.5 billion share should be raised, one of the most difficult problems in the controversy over acid rain.

The money would be spent for a commercial project to demonstrate cleaner methods of burning coal in U.S. factories and power plants.

The sulfur dioxide emissions from such plants, concentrated in the industrial Midwest, undergo changes in the atmosphere and fall to Earth as acidic snow and rain, damaging lakes, streams and forests in the northeastern U.S. and Canada, according to many scientists.

The proposal is similar to a $400 million, three-year demonstration project on clean coal technology that was approved by Congress recently a catchall spending bill and reluctantly accepted by the Reagan administration.

The administration is separately spending about $85 million this year on acid rain research, officials said.

Reagan may find it difficult to reject the findings of a special envoy whom he appointed and ordered to report back to him before Mulroney's scheduled visit here March 18.

Sources said that Mulroney has made repeated personal appeals to Reagan on this subject in the past, and acid rain is expected to be on the agenda of their next meeting.

However, Reagan in the past has resisted expensive acid rain clean-up programs, and may not endorse the new proposal.

A White House official said Reagan would have "no immediate reaction" to it, but would "study" the recommendations.

In a joint statement in Quebec last March, Reagan and Mulroney asked the special envoys to "enhance cooperation in research efforts, including that for clean fuel technology and smelter controls." The clean fuel technology includes various methods of changing the combustion of coal to reduce the sulfur emissions.

Despite misgivings among some advisers, Reagan last year agreed to set up the special envoys on acid rain, partly at the urging of former White House deputy chief of staff Michael K. Deaver, now a private consultant who has said his clients include Canada.

Canada has already launched its own program for controlling acid rain, but contends that the United States is the source of much of the problem. The $5 billion program recommended by Lewis and Davis would be a U.S. effort, although Canada would make other contributions.

The report calls for the two nations to cooperate more in sharing information about acid rain and possible solutions.

Lewis, who is chairman and chief executive of Warner-Amex, the cable television firm, is to present the report to Reagan at the White House today, officials said.

Davis will simultaneously present it to Mulroney and has called a news conference in Ottawa to explain it.

Reagan has privately expressed the view, according to aides, that acid rain is caused by natural processes. While such natural processes as volcanic eruptions, forest fires and decomposition of organic materials produce some of the acid rain, many scientists believe that it is largely the result of man- made pollution from factories and autos.

Lewis told the governors of six New England states Sept. 13 that while some scientific questions remained, "It seems to me that saying sulfates do not cause acid rain is the same as saying that smoking does not cause lung cancer."