This paper deals with the optimization of surface permanent magnet generator (SPMG) for wind generator system (WGC) application. An analytical model based on sub-domain method is introduced in three subdomains. The analytical model is confirmed against 2D finite-element. It predicts the steady-state performance precisely. Various design parameters of SPMG are regarded and then optimized according to the analytical model with the aim of maximizing annual energy, which is obtained from WGC. For operation in the nominal condition, wind data for a specific area is gathered and then the design parameters are educated to maximize annual energy. Beside the main goal of the paper, which is maximum annual energy, other objective functions are also considered to wind up an entire study. Objective functions such as total harmonic distortion (THD), torque ripple (TR), power factor (PF) and losses are included. The proposed analytical model can investigate all possible pole and slot combinations, permanent magnet (PM) thickness, PM arc, inner radius stator and machine stack length as variables for a specific objective function. The proposed approach is much faster than finite-element analysis (FEA) with high accuracy close to FEA.