Secretary of Health, Education and Welfare Patricia Roberts Harris yesterday lashed out at criticism of Social Security, saying it is a good buy and an unbeatable investment for the American worker.

Despite grumbling by some workers that they are not getting their money's worth, Harris told a national symposium on Social Security problems, "The fundamental fact is that workers generally can expect to get back in retirement far more than they contribute during their lifetime."

For example, she said, a young man entering the labor force today at age 22 and earning the median wage (currently $9,654) all his life "will pay $19,557 into the system. He can expect to receive benefits totaling $27,504, or about $8,000 more than his payroll taxes."

Harris said the return for a married worker, whose wife would get benefits based on his pay-in, the return would be much greater -- 3 times what he put in, or $62,600.

In addition, Social Security automatically provides additional coverage "that no private company could ever offer at an affordable cost," Harris said.

This extra protection includes automatic cost-of-living increases in benefits, disability insurance, survivor insurance, portable benefits and nontaxable benefits.

Harris said that some magazine articles have contended that it is possible for a young worker to do better by putting his money into an interest-bearing annuity and holding it there all his life.

This is only possible, she said, if he "never marries, never becomes disabled, does not die prematurely, never does anything but add to his or her investment, and moves ahead to the high-income brackets."

In the House, meanwhile, Social Security subcommittee Chairman J. J. (Jake) Pickle (D-Tex.) prepared for a series of hearings next week on proposals to ease the Social Security payroll tax bite by blocking a tax increase scheduled for Jan. 1, 1981.

The tax, currently 6.13 percent each for employers and employes on the first $22,900 of a worker's earnings per year, will jump to 6.65 percent in 1981, while the minimum taxable wage, gradually rising each year, will reach $29,700 in 1981.

Pickle told a group of reporters recently that if Congress wants to block these scheduled increases, it must find $14 billion a year from some other source to replace the lost revenues -- not an easy job in a day of tight budgets.

Saying that he hasn't any fixed position, Pickle said the hearings will explore the possibility of using general Treasury revenues to strengthen financing, raising the retirement age to 68, cutting student benefits, reducing the general future level of retirement benefits and other measures.