Abstract: Only the stress state of the welded structure of the wind turbine tower under load is analyzed, ignoring the combined effect of heat input and load on the main stress of the weld seam, which increases the error of strain calculation. To this end, research is conducted on the automatic analysis of weld seam strain in wind turbine tower sections under different heat inputs. Firstly, a simplified finite element model of the weld seam of the wind turbine tower section is constructed to calculate the load on the weld seam of the tower; Secondly, the classic 3D double ellipsoid heat source model is used to determine the magnitude of heat input during the welding process of tower tube sections; Once again, analyze the relationship between heat input and load, and calculate the principal stress of the weld seam of the tower section using the hot spot stress method based on the three load components; Finally, based on the changes in heat input magnitude and its impact on the main stress of the weld seam, combined with the calculation results of the main stress of the weld seam, automatic analysis of the weld seam strain is achieved. The experimental results show that the proposed method highly overlaps with the pre-set actual strain values, with a strain value error of no more than 1%, and can accurately monitor the strain state of the weld seam of the wind turbine tower section.