This article aims to the model the influence of geometrical errors (eccentricity and alignment errors) on static and dynamic behavior of helical geared transmission by studying its influence on the load and the transmission errors. For this propos, a dynamic model is developed to geared transmission with 36 degree of freedom (tension –compression , torsion and bending). The equations of motion are solved by combining a time-step integration algorithms with several iterative and Newmark's method .