Provided by the present disclosure is an optical imaging device, comprising: a first optical element comprising an image projection assembly and a first positioning assembly which are integrally formed; a second optical element comprising a light splitting assembly and a second positioning assembly which are integrally formed; and a third optical element comprising a reflection assembly and a third positioning assembly which are integrally formed. The structures of the first positioning assembly, the second positioning assembly and the third positioning assembly enable the image projection assembly, the light splitting assembly and the reflection assembly to achieve optical alignment according to expected optical precision index requirements. In the device described, when each element is assembled on the basis of the respective positioning assembly, the aid of other parts is not needed. As such, the difficulty of installation between the elements is reduced, and while simplifying the installation process, the positioning assembly in each element is integrated with the other assemblies such that the installation error between each of the elements is further reduced, thereby further improving the installation precision of the optical system.