President Reagan's advisers are saying they have devised an orderly system that will overcome bitter arms control conflicts within the administration and make it possible to achieve a nuclear arms agreement with the Soviet Union.

This growing, though unspecific, optimism was reflected by Reagan in a news conference yesterday when he declared he was "very gratified" with recent statements of Soviet leaders favoring elimination of nuclear weapons, saying it was "the same thing that I've been talking about for quite some time."

Administration officials who commented under condition that they not be identified said the process, centralized in an interagency group chaired by national security affairs adviser Robert C. McFarlane, would do a better job than before in resolving the conflicts between various departments that plagued Reagan's first term. They also said that Reagan was far more involved in the process than before, although they acknowledge that he still faces difficult decisions in coming up with a consensus proposal to present to the Soviet Union.

Critics of the administration, including the president's defeated Democratic opponent, Walter F. Mondale, have frequently charged that Reagan is dangerously ill-informed on arms control. Some administration officials have acknowledged this in a backhanded way, saying that Reagan now understands "the fundamental concepts of stable deterrence."

During his first term Reagan was so unfamiliar with these concepts that he expressed surprise when told that his 1982 proposal for reducing strategic nuclear weapons was unacceptable as a basis for negotiation because it would require the Soviets to remove most of their land-based missiles without comparable reductions on the U.S. side.

Now, say officials, Reagan has made arms control a top priority of his administration, reflecting the view urged by advisers that he could leave office as a "peace president" if he succeeds.

"The president's commitment to getting success goes back many years," said McFarlane. "He believes the time to make that possible has come."

Secretary of State George P. Shultz and Soviet Foreign Minister Andrei A. Gromyko are scheduled to meet in Geneva on Jan. 7 and 8 to arrange an agenda for new negotiations to control nuclear arms and space weapons.

Reagan announced Wednesday that Paul H. Nitze would serve as Shultz's adviser on the arms talk, paving the way for Nitze to become the chief U.S. negotiator if Gromyko agrees to umbrella negotiations that the United States now refers to as "coordinated arms control talks."

Administration officials took pains this week to point out that Nitze was the president's choice for the job. One of them said that Nitze, who will report to Shultz, would have "the authority he needs" to explore wide-ranging options on arms control with the Soviets.

An official disputed the view that Reagan disapproved of Nitze's 1982 "walk in the woods" with Soviet delegate Yuli Kvitsinsky during which the two men explored a solution to the removal of intermediate-range missiles from Europe. The official said that Reagan was responsible for "keeping open the channel" that made the walk in the woods possible, and disapproved of the outcome but not the negotiation.

In fact, Reagan rejected the agreement and Nitze was criticized by members of the administration for pursuing this negotiation on his own. When Reagan was asked about it several months later, he appeared to have only a vague recollection that it had ever occurred.

"The president thinks highly of Nitze," said a senior official. "We've put together a decision-making team."

The new process designed to smooth over conflicts is an interagency group created by William P. Clark shortly before he left the national security adviser's post in October 1983 and became secretary of the interior. Chaired by McFarlane, the group is designed to thrash out conflicting positions on arms control and present a consensus recommendation to Reagan. During Reagan's first term consensus was a rarity and the president was frequently presented with conflicting views that he was supposed to arbitrate.

Reagan has held three meetings with the cabinet-level National Security Planning Group chaired by McFarlane to discuss arms control options. These meetings have been described as largely free of friction because potential conflicts have been aired in working-group sessions, including one that was held yesterday.

Nonetheless, many in the administration believe the conflicts will bubble up again if Shultz and Gromyko agree on followup talks on arms controls.

"Reagan is going to have to make some tough decisions before Jan. 7," said one official. "He is optimistic but he has no illusions."

The president reportedly remains unwilling to abandon his interest in a defensive-weapons system even though he has been warned that it could make successful negotiations with the Soviets impossible. However, one official said it is possible that the Strategic Defense Initiative, dubbed "Star Wars," could be traded away.

Yesterday at his news conference, Reagan was asked whether he thought the Soviets genuinely wanted an arms control agreement. He said that "there's no way for me to make a judgment on that until we get into conversation with them."

But in private conversations with aides Reagan has expressed the view that the Soviets are ready to negotiate seriously because it would be costly for them to try to match the United States in space weapons and also because the Soviets now recognize after the election that he has widespread public support.