A low-g-value magnetic self-locking Micro-Electro-Mechanical Systems(MEMS) inertial switch with a threshold of 5g, featuring adjustable threshold and self-recovery capabilities, has been designed. The inertia sensitive unit of this inertial switch consists of a square mass block, a square chessboard-shaped magnet fixed beneath the mass block, and four square Archimedean spiral beams supporting it. The magnet, along with four ferromagnetic fixed electrodes located beneath the moving electrodes and a double-layer planar coil, jointly achieve the functions of magnetic self-locking and threshold adjustment. Simulation analysis is conducted using the finite element simulation software ANSYS. The prototype is manufactured by using laser processing and PCB technology, and the performance of the sample is tested by using a centrifuge. The test results show that the fabricated MEMS inertial switch has a threshold acceleration of 5.27g in the vertical sensitive direction. By applying a current in the range of -0.5 to 0.5 A, the threshold adjustment range is from 6g to 3.75g. The results indicate that this structure can achieve the locking function while enabling self-recovery without external force and allowing threshold adjustment within a certain range.