Sheet stacking is a common production link in the industrial production of modern process, and its stacking quality affects packaging and transportation safety. Aiming at the problem of robot arm grasping and alignment in automatic stacking of polygonal sheets, the work aims to propose a method for calibrating the pose of line feature camera based on mesh screening and put forward the selection criteria of spatial feature points to overcome the problem of point feature accuracy decline caused by insufficient sheet texture. Firstly, the line to be matched was represented by detecting feature points, and then the accurate matching line was obtained by the line feature configuration screening algorithm based on triangular mesh. Next, the transformation matrix was obtained by solving homography matrix, and finally the actual grasping point and transformation angle were obtained by transforming the online sheet image. Through the desktop sheet grabbing experiment and field verification, the error of re-projection was less than 2 pixels, and the error of 1 meter sheet stacking was 0.5 mm. It is proved that this method is effective for feature detection and pose estimation in the process of automatic stacking of sheets.