The utility model provides a precision drive displacement measuring device which comprises an inchworm driver and a measuring element, the inchworm driver comprises a drive shell and an output piece,a sliding opening is formed in the drive shell, and the output piece is installed in the sliding opening in a sliding mode. The driving shell is further provided with a clamping piece and a driving piece. And the measuring element is mounted at any one or more of the following positions: a clamping piece, a driving piece and an output piece. The inchworm driver adopted by the utility model can realize stable, large-stroke and high-output linear driving under the condition that the boundary dimension is small, and the output displacement can be accurately measured through the measuring element.