he securities industry started a nationwide campaign today to persuade Congress to lift or reduce the one-year holding period required before investment profits can be treated as long-term capital gains.

Releasing an opinion survey, leaders of the Securities Industry Association said that the tax law curtails private investment and costs the federal treasury at least $500 million in potential tax revenues.

The survey of corporate executives by Opinion Research Corp. indicates that more than half the business officials questioned would increase investment in stocks, real estate or other investment vehicles during the first year of the tax law change by an average of about $18,700. If the holding period were eliminated, the executives would invest an average of more than $27,000, the survey reported.

Calling the lobbying effort the group's top legislative priority, George L. Ball, president of E.F. Hutton Group Inc., called the proposal "an idea without thorns."

Eliminating the holding period, adopted in 1978 tax legislation, would "aid investors, the economy, the capital formation process and unassailably cut the deficit," said Ball, chairman of the association's tax policy committee.

"This is not a giveaway to the rich," he asserted. "It raises revenues."

The survey of 568 top- and middle-level corporate executives indicated that, during the first year of a six-month holding period, common stock investment from the survey's respondents would rise by $4.1 million. Were all members of that income class to invest proportionally, total new investment could rise by about $50 billion during the same period, Ball said.

"Rather than being a radical proposal, a reduction in the holding period would restore the law back to 1976. This proposal is not 'voodoo economics'," he said.

Until 1976, investments had to be held for six months to be labeled as long term for taxing purposes. But in 1976 Congress lengthened that period to nine months for 1977 and to a year beginning in 1978. As part of its tax bill last year, the Reagan administration, until late in the debate over the legislation, urged that the six-month period be adopted.

SIA President Edward I. O'Brien said the association will push the plan in meetings with key legislators, and in a national campaign, which will include mailing fliers to investment company clients.