The invention discloses an in-place measurement device of grinding processing of a crankshaft and relates to the technical field of machinery processing measurement. The measurement device comprises a first slide rail, an installation plate, a rotation rod, a support plate, an adjusting nut, a screw, a bearing, a hydraulic telescopic rod, a pressure adjusting rod, a base, a second slide rail, a driving mechanism, a back plate, a support device, a support rod, a foldable plate, a measuring device and a probe. Through the overlapping setting of the first slide rail and the second slide rail, the driving mechanism is enabled to move in a front, back, left and right manner on the top of the installation plate. The height and the angle of the installation plate can be adjusted, so the measurement range of the measurement device is enlarged. A micro-telescopic cylinder telescopes to drive a left side measurer to move, clamping measurement of the two groups of measures is facilitated. The measuring device and the support device move synchronously, so the support device will not affect the normal measurement of the measures. According to the invention, normal operation of workers is not affected; a production mechanism is not affected; and detection efficiency is improved.