Abstract: In order to realize the on-line detection of the stress during the plough cutter operation process of the coal plough, a dfficult problem to set the electric p ower on the coal plough was overcame and a stress detection system of the self power supply was provided based on a piezoelectric vibration energy harvest device.T he vibration energy in the operation process of the coal shearer could be effectively converted to the electric power to ensure the detection device and the wireless sign al transmission device could be normally operated in a long time.The detections with several periods showed that the self power supply performances of the detection s ystem was stable and could realize the 3D load on-line detection of the plough cutter.The 3D load variation curve within 100 s was obtained.The analysis showed that th e ploughing and planing resistances (Y dimension) , the extrusion force (X dimension) of the coal wall and the lateral force (Z dimension) of the coal wall would be redu ced in a size-dependent. The load fluctuation would be in the same law, the test results were closed to the actual performances and the detection system could have the high accuracy.