Broken coal body methane desorption device, including breaker and methane desorption device, the motor passes through the belt and is connected with the runner, the eccentric shaft is fixed on the runner, the weight passes through connecting rod and eccentric shaft connection, the weight is tight with the surface subsides of support smooth inner wall, coal sampling mill space sealing, the lower extreme is the base, the upper end is the weight, the left end is equipped with sealed lid, and be connected with high -pressure gas bottle and vacuum pump through the tee bend valve, be equipped with switching valve between tee bend valve and the high -pressure gas bottle, the manometer, relief pressure valve and stop valve, be equipped with vacuum meter and stop valve between tee bend valve and the vacuum pump, be connected with stop valve and manometer between desorption instrument and the coal sampling mill, the utility model has the advantages of being simple in structure and convenient in operation, crushing effect is good.