The invention discloses a multi-camera calibration and parameter optimization method based on a sphere projection common tangent line. The method includes obtaining the coordinates of the sphere center projection on the phase plane according to the collinear principle of the sphere projection common tangent line intersection point and the sphere center projection point; 2, through the combinationwith the sphere center projection, obtaining the inner parameters and the outer parameters of the camera through the algebraic relation between the image of the absolute quadratic curve and the projection of the sphere; 3, representing the projection of the sphere by using the oval parameters, dividing the error between the projection curve and the reprojection of the projection curve into two relatively independent parts accordingly, and adopting a nonlinear optimization method for gradually optimizing the deviation of the two parts to obtain a final calibration result of the camera; 4, unifying the calibration results of the multiple cameras to the same world coordinate system through the matching method, and completing the multi-camera calibration. According to the method, the parametergeometric significance is reserved in the solution process, the calibration precision is high, and the simultaneous calibration of the multiple cameras is simply and efficiently completed.