NEW YORK, December 15--The United Nations Assembly, driving toward adjournment after launching a world arms limitation program, hurdled one of its last major obstacles tonight as it over-rode Russian opposition and approved a draft constitution for an international Refugee Organization.

After nearly four hours of debate, the Assembly approved the blueprint for the refugee organization and its $160,000,000 budget by a vote of 30 to 5. Before it becomes effective, the constitution must be ratified by 15 nations or enough countries to contribute 75 percent of the total budget, in the event the first 15 are small contributors.

At the same time, informed quarters said the United States delegation and probably France and China were prepared to support a Ukrainian proposal that the 1947 session of the Assembly beheld in Europe. The Ukrainian resolution, last item on the agenda, was said to have a fair chance of approval. Its acceptance would not affect the assembly's earlier decision to make its permanent headquarters in New York City.

The refugee battle opened the way for speedy action on the remainder of the agenda.