The invention discloses an aspheric surface profile measuring device and method based on the most proximate circle theory. The measuring device comprises an L-shaped bed body, the outer side f the vertical portion of the bed body is connected with a torque motor through a flange, a rotary shaft of the torque motor penetrates through the vertical portion of the bed body and is connected with a rotary support, the rotary support is closely attached to the lower half portion of the inner side of the vertical portion of the bed body, a rotary hand wheel is disposed on the top of the rotary support, a transverse T-shaped Z-direction moving support is connected with a sliding rail on the side face of the rotary support, a sliding rail on the top plane of the Z-direction moving support is connected with a Y-direction moving platform, a sliding rail on the top plane of the Y-direction moving platform is connected with an X-direction moving platform, a workpiece fixing table is fixedly arranged on the upper surface of the X-direction moving platform, and a to-be-measured element placement platform is arranged on the upper surface of the workpiece fixing table. The problem that in the prior art, aspheric surface optical parts are difficult to detect is solved.