Robert C. McFarlane, President Reagan's special Middle East representative, is returning here this weekend for talks with Secretary of State George P. Shultz and other administration officials about the situation in Lebanon, the State Department announced yesterday.

McFarlane has been shuttling around the Middle East in an effort to help Lebanese President Amin Gemayel's government establish authority following an outbreak of civil violence in Beirut this week. The U.S. Marine unit serving with the multinational peacekeeping force there suffered two dead and 14 wounded during the fighting.

The Lebanese army appears to be asserting control over the city. But new violence could break out between Lebanese Christians and Moslem Druze militias in the Chouf Mountains when Israeli occupation forces begin withdrawing from that area in the next few days.

McFarlane is trying to work out an agreement that would allow the Lebanese army to enter the Chouf with the approval of the Christians and Druze. That is expected to be the principal subject of his discussions here.

Department officials said he was expected to meet with Shultz today, but they added that the session could be delayed because of the administration's efforts to respond to the reported shooting down of a South Korean jetliner by the Soviets.