With plenty of distributed generators connected to distribution system, island operation can be used as a new fault recovery approach to ensure the power supply of critical loads. A heuristic islanding algorithm based on distance-weight was proposed, taking the maximum recovered critical load as the main target, considering the pact of various operation constraints and uncontrolled loads of the distribution networks, introducing distance-weight which represents the distance between the objective load and the island to find out which load is the nearest to the current island and should be recovered first. The initial island is composed of all the DGs and some branches between them, and then enlarged by merging the nearest load among all the considered loads. Finally, it will get security assessment and be regulated. Simulation results have demonstrated that the proposed algorithm can generate a reasonable islanding scheme after a fault occurs.