MORRISTOWN, N.J. (AP) _ A state judge ruled today that the husband of a woman who has lain in a nursing home for six years, hopelessly brain-damaged by an anesthesia accident, could remove the feeding tube that has been keeping her alive.

Superior Court Judge Arnold M. Stein, in New Jersey's latest right-to-die case, said the husband of 31-year-old Nancy Ellen Jobes had proved she was in a ''persistent vegetable state with no prospect of improvement.''

If competent, he said, Ms. Jobes ''would not want to be sustained in this mental and physical condition by artifical tube feeding.''

Ms. Jobes suffered irreversible damage on April 2, 1980, when her brain was denied oxygen during an operation to remove a fetus killed in an auto accident, according to court documents.

Her husband, John H. Jobes, of Boonton, and her parents, Robert and Eleanor Laird of Parsippany-Troy Hills, asked that she be allowed to die, but officials at Lincoln Park Nursing and Convalescent Center refused to remove the tube.

Stein excused those involved in the removal of the feeding tube from criminal or civil liability. He said Lincoln Park has the right to refuse to participate or to allow it to take place on its premises.

But he said nothing could be done for 20 days to give the nursing home time to appeal.

Mrs. Jobes' mother said of the ruling, ''It's the first step in letting Nancy out of this world. ... It's been a long ordeal for the family and for Nancy.''

In making his decision, Stein had to weigh whether Mrs. Jobes is in a persistent vegatative state, as her family contended, or a step above that, severely brain damaged. Doctors disagree on her status.

Another key issue was what Mrs. Jobes would have wanted had she been able to express her wishes. Four witnesses testified that she had said she would never want to be maintained in her current condition.

Stein also had to consider whether the case falls under the guidelines of two landmark state Supreme Court ''death with dignity'' rulings in the cases of Karen Ann Quinlan and Claire C. Conroy.

During a seven-day trial earlier this month, Stein heard conflicting testimony from doctors and experts on medical ethics.

The nursing home's attorney, Raymond Tierney, said the home felt that withdrawing food and water from Mrs. Jobes would be ''illegal, unethical and immoral.''

The family's lawyer, Paul Armstrong, said it was Mrs. Jobes' constitutional and common-law right to be allowed to die.

Doctors testified that Mrs. Jobes is in good physical condition, but has no hope for recovery or cure. They said she could remain in her present condition as long as she continues to be fed.

In the Quinlan case, the Supreme Court in 1976 recognized a person's right to die with dignity and allowed the ''vegetative'' Miss Quinlan to be weaned from her respirator. She was expected to die within a year, but survived nearly a decade without the device. Miss Quinlan died June 11, 1985

Last year, New Jersey's highest court erased any difference between respirators and other extraordinary devices, including feeding tubes, with its ruling in the Conroy case.

The court affirmed a competent person's right to refuse all medical care, even if it would result in death. In cases where a patient is incompetent and cannot express his or her wishes, the court required a unanimous decision on removing treatment by the legal guardian, attending physician and others.

Miss Conroy, a semi-comatose, incompetent and terminally ill nursing home patient, died in 1983 during a court battle over her nephew's request to remove her feeding tube.