The ghost order phenomenon caused by tooth surface waviness induced by grinding and internal gearing power honing has become a significant noise source in electric vehicle gearboxes. However, there are few reports on the analysis mechanism of waviness, and gear manufacturers cannot determine the root cause and control strategy of waviness-induced ghost steps. In this study, an evaluation method of the effect of waviness on gear meshing noise is proposed based on the theoretical model of tooth waviness. By taking the calculation of basic gear parameters as a basis, an ideal and unbiased mathematical model of the waviness of the workpiece's tooth surface is established. The FFT method is used to fit and analyze the full-tooth waviness curve, to elucidate the fundamental relationship between the waviness characteristics and the gear meshing noise. The results show that the waviness analysis can accurately determine the noise-related strange order in the contact path and reveal the characteristics of the waviness curve leading to the abnormal order. This study provides valuable insights to establish the correlation between tooth waveforms and gear mesh noise.