Abstract: With connecting a lot of flexible loads and distributed generations into distribution network the operation reliability of the latter is affected by multi uncertain factors. For this reason, a method to analyze the reliability of active distribution network considering the response strategy of flexible loads was put forward. Firstly, by use of Ito stochastic process the timing uncertainty of the output of distributed generation was described. Secondly, according to the feature of flexible loads and the constraint of transfer capacity based on the first order stochastic dominance theory a rolling response strategy of flexible load was proposed. Finally, by use of Markov chain and Monte Carlo method the reliability analysis for the improved RTBS6 system was performed. By this computing example, the response strategy of different flexible loads and the impact of switched-in capacity of the distributed generation on the output of flexible loads and reliability were analyzed to provide reference for the analysis on the response of flexible load.