Abstract: After a major power outage, using the local distributed generators of the urban distribution system to restore critical loads is an effective method to mitigate outage and improve the resilience. The loads in urban power grid include the customer loads that can only be functioned with the joint support of various resources such as electricity, water and gas, as well as the critical infrastructure loads such as traffic lights and water pumps. Besides, there exists closed interdependency among power grid, customer loads, and critical infrastructure loads. In this paper, a multi-period restoration method for distribution system critical loads considering the load function requirements is proposed. On the load side, the power, water, and gas demand of customer loads and the power demand of traffic loads are considered. On the grid side, the operation constraints of power distribution system, water network, and gas network are considered. On the source side, the flexible access of mobile resources and limited resources of local distributed generators are considered. The results of case studies show that the proposed method can maximize the social function of various loads and realize the optimal allocation of limited generation resources.