Based on 2.5°×2.5° NCEP/NCAR reanalysis data and the improved local meridional circulation model, quantitative diagnosis for the mechanism was performed on a continuous autumn rain event in Henan Province from 5 to 19 September 2011, and evolution characteristics of the main physical factors for the continuous autumn rain event were proposed by means of lag correlation analysis of the upward branch of a local meridional circulation and precipitation over Henan. The results showed that, (1) latent heating, average meridional temperature advection, zonal advection of westerly momentum and average zonal temperature advection are the main physical factors which caused the continuous rainy weather to occur over Henan Province in September 2011. (2) The latent heating and average zonal temperature advection are the main physical factors for the start of the rainy weather; zonal advection of average westerly momentum and average meridional temperature advection as well as average zonal temperature advection are the physical factors for the continuous rainy weather; latent heating, zonal advection of average westerly momentum, average meridional temperature advection and average zonal temperature advection are also the main physical factors for the continous rainy weather ending.