When using the wide-angle imaging system to obtain large flat-screen scene information close and tilt, images will produce nonlinear geometric distortion consisted with perspective distortion and radial distortion. Based on imaging the grid template and the cross ratio invariability of collinear points with perspective projection, the radial distortion model parameters by nonlinear optimization is obtained, and the radial distortion is corrected. The transform matrix is built to calculate the transform coefficients by perspective transform method and correct the trapezium distortion. The non-linear geometric distortion is corrected for the images of square template with the side length as 1200 mm, the focal length of wide-angle lens as 14 mm, and the camera tilt angle as 43.34°. By the accuracy analysis of points in different locations, the relative error of identification points are less than 1%, the results show that the algorithms are suitable for the correction of nonlinear geometric distortion and have a high correct accuracy.