Modal analysis of gear mainly relies on numerical modal analysis and experimental modal analysis,it claims a tedious solving process and cannot acquire the coupling relationship of gear parameters with modal frequency and vibration mode directly.The constraint modal models of double circular-arc gear were constructed according to the numerical calculation theory of modal in order to further master influences of major gear parameters on natural frequency;the first 6-orders vibration modes were analyzed and influencing factors of various factors on modal frequency were calculated through orthogonal experiment and variance analysis;the influences of teeth number,modal number,helical angle and teeth width of double circular-arc gear on constraint modal of double circular-arc gear were analyzed quantitatively.The results show that teeth number is the primary influencing factor of natural frequency,followed by modal number,helical angle and teeth width successively;the centralized single nonlinear regression model was used to calculate the experimental results,a calculation model of constraint modal frequency of double circular-arc gear was established to realize the fast calculation of the constraint modal,and the calculation accuracies of 1 order frequencies were compared and verified.The research results provide reference for the study of vibration and noise characteristics of double circular-arc gear comprehensively.