Gears are essential components that transmit motion and power through the interaction of engaging tooth surfaces. With continuous operation of gears under complex working conditions, gear wear inevitably occurs. The precise measurement and evaluation of wear volume serve as the foundation for gear wear research and the enhancement of wear resistance. Firstly, this study conducted FZG gear wear tests, and after each test phase, a roughness profiler was utilized to acquire tooth profile data. Subsequently, the acquired tooth profile data were subjected to orthogonal distance least squares fitting, and the measured tooth profiles were mapped into the gear coordinate system to obtain the tooth profile deviation curves. Then, an iterative filtering algorithm was designed to extract the upper contour line of the tooth profile deviation curves. Finally, the impact of factors like iterative stopping conditions and cutoff wavelength on wear volume evaluation results was investigated, and principles for selecting these factors were presented. Utilizing the proposed method, the evaluation results for the working tooth profile wear volume have been successfully obtained. The influence of instrument measurement noise and surface roughness on the evaluation results is effectively eliminated, thereby significantly improving the accuracy of gear wear volume assessment. The precise evaluation method for gear wear volume based on the iterative filtering algorithm proposed in this study enables accurate and reliable measurement of gear wear volume. This method lays a solid foundation for subsequent gear wear modeling and prediction.