The invention discloses a cross-optical-axis grating projection measurement simulation system (the so-called cross-optical-axis means that the optical axis of the projector in the system axis and optical axis of the camera cross each other in terms of positions, which overcomes the shortcoming of an existing simulation system that the two axis cross at a point). According to the invention, the Windows system is used as the development platform; through the backlight ray tracing method, the use of the computer programming language, and with the writing of a grating projection module, the simulation of a to-be-tested object and working station module and an image acquisition module, a grating projection measurement simulation system with high precision comes into being. The simulation system does not require that the optical axis of the projector intersect with the optical axis of the camera, which can realize the simulation of the cross-optical-axis grating projection measurement system. The system can simulate the position of an object appearing in the shadowed area in the process of measuring, and for the determining of the shadowed area on the surface of the object and the shadowed area of the working station, different determining methods are applied, which increases the determining accuracy and the determining speed.