Aiming at the problem of steady state voltage stability caused by distributed generation access to distribution network, the voltage stability of active distribution network including distribution network is mainly investigated in the paper. To reflect system voltage stability of each node, a voltage stability index method is firstly proposed according to the results of power flow calculation for the whole distribution network. Considering distributed generation as a negative load direct injection, different models of distributed generation in power flow calculation are then established. Finally, taking the typical wind power of distributed generation for example, active distribution network of IEEE33 node is simulated, and different fan efforts, fan access and active output fluctuation influence on the voltage stability of active distribution network system are analyzed in detail. The simulation results show that the distributed network with distributed generation can effectively improve the voltage stability.