The invention discloses a strip shape signal error compensation method based on strip shape detection roll installation accuracy, which comprises the following steps of: constructing a strip shape signal compensation model aiming at strip shape detection roll installation errors based on a geometrical relationship between a strip shape detection roll and a guide roll or a winding drum and a cold rolled steel strip shape detection theory; and aiming at two installation ways, i.e. a fixed wrap angle way and a dynamic wrap angle way, establishing a corresponding tensile stress dynamic deviation calculation formula to compensate online strip signals of cold rolled steel strips in real time. By considering the influence of the strip shape detection roll installation accuracy on original strip shape signals, the online strip shape detection accuracy of a contact-type strip shape detection instrument is improved to the utmost extent, the actual strip shape situation of the online cold rolled steel strips is more really reflected, the strip shape control performance of a rolling mill is improved, and stable, reliable and real-time strip shape data can be provided for a strip shape closed-loop control system.