As traditional interference-based measurements can not be suited to measure the surface profile of the Wolter Type I revolving aspheric mirror, a new method was proposed to measure this kind of mirror in this paper. On the basis of a Long Trace Profiler (LTP), a new measuring device was also established by introducing a pentaprism into the scanning mechanism for ray turning. The working principles, structure parameters and data processing algorithms of the device were investigated, then a standard plane mirror was used as the reference to calibrate the device. Finally, a mirror sample was measured to verify the measuring device. Experimental results indicate that designed device can achieve the slope error of RMS 6.7 μrad , repeatability of 0.75 μrad and the height profiles of PV 0.24λ and RMS 0.07λ, which meets the design requirements basically.