The voltage quality of the distribution network may be seriously impacted by distributed generations (DGs) and load in microgrid. How to accurately analyze the impact of power flow from microgrid integrated into the distribution network, to improve the voltage quality of the distribution network, are needed to be further studied. A novel microgrid power flow calculation and optimal control method based on multivariate stochastic factors fusion-sensitivity (MSFF-sensitivity) is proposed in this paper. The multivariate stochastic factors fusion (MSFF) function is firstly developed to extract the stochasticity and correlation of power flow among different stochastic factors in the microgrid; Further, the fusion-sensitivity (F-sensitivity) for the stochastic power flow of the microgrid integrated into the distribution network is created to precisely characterize the influence of various stochastic factors in the microgrid on the power flow of the distribution network. Based on this, the power flow of the distribution network is optimally controlled. Finally, the algorithm verification shows that, compared with the traditional microgrid power flow analysis and calculation method, the method proposed in this paper is more applicable to microgrid. By optimally controlling the power flow of the microgrid， the voltage quality of the distribution network can be improved.