<p>A method is proposed to address the challenge of computing the meshing stiffness of non-circular gears (NCGs) under load conditions. The tooth surface equation of NCGs is derived in accordance with the forming principle. In consideration of the principles of bearing contact finite element analysis (FEA) of NCGs, the meshing stiffness of tooth surface meshing nodes is incorporated into the calculation of the meshing stiffness. The variation laws of integrated elastic deformation and normal contact force during meshing process are analysed, with the objective of obtaining the meshing stiffness of NCGs. The influence law of load on meshing stiffness and transmission error (TE) is determined. The results demonstrate that the meshing stiffness and TE of NCGs exhibit a regular variation, with the load exerting a significant influence on both meshing stiffness and TE. As the load increases, meshing stiffness and TE both show an upward trend. This article provides the basic conditions for the dynamic analysis of NCGs.</p>