Abstract: Using conventional observation data and ERA5（0.25° × 0.25°）reanalyzed data to analyze typhoon Maysak,the results indicated that the subtropical anticyclone was abnormally powerful.It combined with a blocking high on the north side to create a high-pressure barrier.As it moved northward,the typhoon Maysak interacted with the subtropical anticyclone,causing an increase in baroclinic properties and vortex enhancement due to its interaction with cold air in the middle latitudes.The Maysak brought a significant amount of water vapor to Heilongjiang,where it converged with the middle and low-level jet stream to form a strong water vapor convergence area and belt.The high and low-level jet flow combine to create a strong vertical circulation,resulting in a very high vertical ascending velocity.The subtropical anticyclone extended to the northwest,and the direction of the steering flow and thermal wind turned to the northwest-southeast direction,prompting the Maysak to move to the northwest and pass through Heilongjiang after landing,which was the main reason for the heavy rain in Heilongjiang province.By analyzing the three-dimensional structural changes of the physical quantities such as the vorticity,divergence,vertical velocity,potential temperature,and wet potential vorticity of the typhoon center,we can understand the variability process of the typhoon during its northward landing and the cause of the asymmetric structure of precipitation.