WASHINGTON (AP) _ Eighty-four percent of the American people feel personally threatened by the huge federal deficit and favor raising taxes and cutting spending to solve the problem, pollster Louis Harris said today.

A poll of 1,253 adults also found 61 percent willing to give up some tax benefits as a price for a simpler income tax system. By a 63-26 margin, they said cutting the deficit must take priority over tax overhaul.

''Americans are sending their leaders an important messasge: Get moving on both fronts,'' Harris told the congressional Joint Economic Committee in releasing results of the February survey.

The survey conflicts with a widespread feeling in Congress that voters are not worried about deficits in the range of $200 billion a year as long as the economy is growing, inflation is relatively low and interest rates say well below the historic highs of five years ago.

By a 90-4 margin, those responding to Harris's questions consider the deficit a serious problem. Three out of four feel it will increase interest rates and inflation over the next 12 months; 68 percent fear it will boost unemployment; 69 percent say it will slow the rate of economic growth.

Even more striking, 49 percent view the deficit as a very serious threat to their personal well-being; 35 percent called it a somewhat serious threat. Only 11 percent said they did not feel seriously threatened.

''The nuances of public finance may still be abstract for most Americans but increasingly, people are linking the level of federal deficits to their own well-being - and concluding that the deficit has to be cut,'' Harris said.

How? Fully 60 percent disagree with President Reagan's position that the deficit can be controlled without raising taxes, even though 82 percent of those polled prefer spending cuts. And a plurality favors limiting deductions for charitable contributions, eliminating interest deductions on vacation homes and on personal credit costs and reducing business tax breaks to finance the deficit cut.

But those polled were more willing to give up their own tax breaks as the price for a simpler tax system, as several proposals would do. For example, by a 66-27 margin they would accept limits on the charity deduction; by 65-27, they would limit deductions for auto loans and other personal debt; by a 52-40 margin, they would even accept taxation of employer-financed group health insurance.

The poll has a margin of error of plus or minus three percentage points.