The invention provides a wheel speed measuring device, which comprises a first encoder fixing mechanism, an encoder and a second encoder fixing mechanism, wherein the first encoder fixing mechanism comprises a mounting disc, a adjusting frame and a plurality of positioning frames; two end surfaces of the mounting disc are provided with a mounting column and a mounting ring separately, an internal threaded hole is formed in the mounting column, a communicating hole is formed in the mounting disc, and the communicating hole is communicated with the internal threaded hole; the adjusting frame comprises a positioning block and a positioning shaft, and the positioning shaft is provided with external threads matched with the internal threaded hole; each positioning frame comprises a clamping-in block, a positioning ring and a connecting rod, and the clamping-in block and the positioning ring are arranged on the connecting rod; the encoder comprises a code disc and a mounting shell; and the second encoder fixing mechanism comprises an adjusting rod and a mounting frame, the adjusting rod is connected with the mounting shell, and the adjusting rod is mounted on the mounting frame in a movable manner. The wheel speed measuring device is convenient in use, and can achieve the precise speed measurement of different wheels.