In order to solve the problem of measuring the position and posture of a coal mine roadheader, a set of reverse coaxial industrial cameras and strapdown inertial navigation system were assembled into a bias measurement unit. Combining vision measurement and inertial navigation technology, a real-time pose measurement method was proposed based on space vector constraints. In this method, the spatial vector of the light spot of laser pointer, the spatial vector of the light spot of palm face and the attitude information of roadheader were measured by the deviation measuring unit. Space vector constraint equation and coordinate system conversion were established. The location information of the roadheader was obtained. Theoretical analysis and experimental verification were carried out. The results show that, the six degrees of freedom information of the real-time position and posture of the roadheader can be obtained by this method. This method can be used to measure the position and posture of coal mine roadheaders, and has broad application and development prospects.