The invention discloses an in-situ test system of nitride light emitting diode magnetoelectricity stress coupling. The system comprises a nitride light emitting diode, an additional current source, an XRD test component and a magnetic field generation apparatus. The system is characterized in that a magnetic material is formed on a side wall of the nitride light emitting diode; a current is added to two ends of a P-type electrode and an N-type electrode of the nitride light emitting diode and the nitride light emitting diode is placed on a sample stage of the XRD test component; the magnetic field generation apparatus generates a magnetic field around the nitride light emitting diode so that the nitride light emitting diode generates a magnetic field-electric field-stress coupling effect; XRD single crystal diffraction is used to test a lattice constant of the light emitting diode in a magnetic field and electric field change process in an in-situ test mode so as to carry out in-situ control on the magnetic field and the electric field and regulate and control a stress change of a nitride so that the light emitting diode acquires highest luminescence efficiency.