Wholesale prices fell by a full percentage point in January, the largest one-month decline since this measure of inflation was first calculated in 1947, the Labor Department reported yesterday.

Sharp declines in energy prices led the way, with costs of gasoline, fuel oil and natural gas all down from December's levels, the Labor report said. Food prices also fell, although at a more moderate rate.

White House spokesman Larry Speakes hailed yesterday's report as "striking confirmation of the progress that has been made in reducing the underlying rate of inflation. This is good news, and indicates that the administration and the Federal Reserve, working on the same wavelength, achieved these results."

In recent weeks, some Wall Street financiers have cautioned that the rapid monetary growth of the past few months could worsen inflation in the future.

But President Reagan this week told businessmen that he "felt Federal Reserve Chairman Paul A. Volcker was fully aware of the dangers of reigniting inflation and he intends to take a middle course" that will allow recovery without higher inflation, according to Robert Thompson of the Chamber of Commerce, one of the businessmen who met with Reagan.

Yesterday's release on prices showed that fears of renewed inflation were "excessive and completely unfounded," Commerce Department chief economist Robert Ortner commented. "We certainly have a good period of time ahead of us before we need to worry about renewed inflation."

The drop in producer prices in January left them only 2.1 percent higher than they were a year earlier. During 1982 they rose by 3.5 percent, the smallest annual increase since 1971, when wage and price controls were in effect.

Since President Reagan took office there has been a dramatic slowdown in inflation. The deep recession has been a major factor holding down price increases, together with abundant harvests and declining dollar prices for oil.

Energy costs dropped by 4.2 percent last month, after a 0.9-percent drop in December. By contrast, these prices had risen an average of about 2 percent a month in the six months up to November.

One reason for the energy price rises last year was that natural gas prices soared. Last month, however, these prices declined by 2.7 percent, helped by the mild weather, analysts said. Home heating oil costs plunged by 9.7 percent in January, and gasoline prices dropped 3.3 percent, the report said.

Food prices edged down by 0.2 percent in January, the Labor report said. These prices have moved little in most recent months, and are now only 0.7 percent higher than a year ago.

Further good news on inflation may lie ahead, analysts said yesterday. The administration has predicted that consumer prices will increase 5 percent by the last quarter of this year, compared with the last quarter of 1982. Consumer prices rose 4.4 percent on the same measure during 1981-82.

However, economist Allen Sinai of Data Resources Inc. said yesterday that the producer price report "suggests 1983 is going to be a year of surprisingly low inflation, just as was 1982."

He pointed out that much of the dampening effect on prices and wages from recession is felt after the recovery has begun. In addition, oil prices are declining further in the wake of disagreement over pricing and production among oil exporting nations.

While another sharp decline in inflation is "too much to hope for," according to Donald Straszheim of Wharton Econometrics, "we're a long way from any plus-ones," he said.

The price index for "intermediate" goods, which are used in production, fell by 0.3 percent during January, the release said. These prices were unchanged during December, and climbed by 0.3 percent in November.

Crude materials prices dropped by 0.3 percent in January after declining by the same amount in December. They have dropped for seven of the past eight months.

As the economy picks up steam in coming weeks, most analysts expect increases in some commodity prices that are sensitive to demand. Steel scrap prices, for example, have already picked up sharply.

However, such increases would not necessarily signal a widespread upturn in inflation, analysts say. High unemployment, together with considerable unused capacity in industry, is likely to depress wage and price increases for some time, they say.

The 1 percent decline in the producer price index for finished goods in January followed increases of 0.2 percent in December and 0.6 percent in November, the Labor release said.

This left the index, before seasonal adjustment, at 283.6 (1967 is equivalent to 100).