The Vatican has ruled that Roman Catholic Church cannot change its law barring women from ordination to the priesthood.

The 18-page declaration of the Vatican's Sacred Congregation for the Doctrine of the Faith, released yesterday, has dashed the hopes of hundreds of women who aspire to the priesthood and thousands of other Catholic, men and women, who have organized to support their struggle.

It raises an obstacle to reunification moves, particularly with Anglicans and Lutherans, but will be reassuring to Orthodox Christians who have viewed with dismay last year's decision of the Episcopal Church in this country to ordain women.

The Vatican declaration, which was completed and approved by Pope Paul V1 last October but not released until yesterday, cited a number of reasons for continuing the Catholic Church's refusal to ordain women to the priesthood:

Christ was male; the priest, in celebrating the eucharist (holy communion) functions as a stand-in for Christ, the document said. "The Christian priesthood is therefore of a sacramental nature; the priest is a sign, the supernatural effectiveness of which comes from the ordination received, but a sign that must be perceptible and which the faithful must be able to recognize with ease," the document states.

Christ "did not call any women to become part of the 12 (apostles)" even though "he broke with the prejudices of his time by widely contravening the discriminations practiced with regard to women."

The apostles, early fathers of church, did not ordain women to the priesthood.

The document paid tribute to "the great number of women who have consecrated themselves to the Lord for the exercise of charity or for the missions, and the Christian wives who have had a profound influence on their families, particularly for the passing on of the faith to their childre."

(Excerpts from the declaration may be found on page C8).

Archbishop Joseph Bernardin, president of the National Conference of Catholic Bishops in this country, issued a statement urging those likely to be disappointed by the Vatican document to "read, study, and pray over this document in order to discern how much more, beyond a simple prohibition, it is really saying to us all."

He said the declaration did not reflect "lingering notions of make superiority." The church "fully recognizes the equality of women and men, repudiates unjust discrimination base on sex, and encourages efforts to bring women increasingly into roles of leadership in the church." he added.

Although yesterday's document left no doubt that, for the time being, women may not become Roman Catholic priests, it could not be determined whether he question is closed forever.

At a news conference here yesterday the question was put twice to Msgr. Richard K. Malone, a staff member of the U.S. Bishops' conference who was a staff member of the Vatican congregation that issued the document.

"There are all sorts of signs that the document is taking a very official stand," he said. But he stopped short of saying that future popes could not take a different view of the matter.

Msgr. Malone indicated, in response to a question that the Vatican congregation that developed the document was not in unanimous agreement on it.

Yesterday's document supercedes a study released last year by the Pontifical Biblical Commission, which said there was no biblical basis for barring women from the priesthood.

The document did not deal with the question of permitting women to become deacons, a lower order. A Vatican statement said this question "should be kept for the future and not touched upon in the present document."

The Vatican declaration was largely prompted by the persons who will be most disappointed by it: women aspiring to the priesthood and their supporters.

Msgr. Malone said that the Pope directed the congregation to study the question because of "requests from bishops around the world" who in turn have been importuned by individuals and groups pressing for change in church law.

The Catholic Church has also been sharply criticized by women's rights advocates in and out of the church who charge that church refusal to ordain women implies a second-class status for women.

Last fall's national Call to Action Conference of the Catholic Church, held in Detroit, urged, among other things, opening the priesthood to women.A 1975 conference on ordaining women has developed into a national organization with 900 dues-paying members.

Dolly Pomerleau, an officer of the group, called the Women's Ordination Conference, said here yesterday that the group would not take the Vatican's statement as final. "They're trying to make it sound like the discussion is closed," she said.

"We've heard from the hierarchy, but the Vatican Council also spoke of the church as the people," she said. "We've only had one side of the discussion."

Another group, the Christian Feminists, has called for a "week of continual prayer" by all women, beginning Feb. 6.