This study aims to improve the transmission stability and obtain the stable working range of the moving web on oblique supports in the preparation of high-speed printing press. The oblique coordinate system was adopted, and the differential quadrature method was used to analyze the influence of oblique support angle, aspect ratio, and tension ratio on the stability of the system. The complex frequency of the system decreases with the increase of the oblique support angle, and the critical speed of the system does not change with the tension ratio and the aspect ratio. The stability intervals of the system are 0 m/s<v<27.5 m/s and 0 m/s <v<27.9 m/s respectively. The oblique support angle has an important influence on the stability of the moving web. The critical speed and stable working interval of the moving web provide theoretical guidance for the stable operation of high-speed printing press.