Agreement to plans for withdrawal of 115,000 Soviet troops from Afghanistan may mean an end to some hostilities, but it doesn't spell an end by any means to all the problems in the war-torn country.

High on the list is what to do about 5.5 million Afghan refugees, the world's largest war refugee population. The long civil war killed about one million people and created five million refugees, Two million of that number fled to Iran and three million to Pakistan.Estimates of Afghanistan's total population vary from about 15 million to 19 million. If the lower number is correct, then about one-third of the country's people have been made refugees by the war. Another two million to three million Afghans are believed to have been driven from their homes but are still living inside the country.

Unlike most of the world's refugees who are looking for other countries in which to reside, the Afghan refugees just want to return to their own homes.

While the Soviets will begin leaving the country May 15, this does not signal the end of fighting there. That is because rebel forces have rejected the peace pact and vowed to continue efforts to overthrow the communist Kabul government being left behind. Most experts don't think the puppet government will survive.

With several rebel groups expected to continue fighting each other in Afghanistan, the resettlement of refugees will be difficult.

The U.S. has provided arms, finances, and other assistance to rebel groups and should continue doing what it can to aid the resettlement of refugees. The United Nations has launched a worldwide appeal for aid.

If there is a mass return of refugees, hundreds of millions of dollars will be needed within the next 12 months.

The Reagan administration, which operates a $45 million cross-border operation providing food, medical supplies, farm tools, and other aid to the resistance, has not indicated whether it also will contribute to a U.N.-led repatriation program.

Having armed the rebels and pushed so hard for Soviet withdrawal, the U.S. ought to take the final step and do what it can to help resettle the refugees, instead of leaving them to fend for themselves.