In order to solve the problem that the low-g omnidirectional MEMS inertial switches cannot recognize the load direction, a nickel omnidirectional MEMS inertial switch with identifiable load direction and uniform in-plane threshold distribution was designed. The switch is mainly composed of a spring–mass system, four independent flexible radial electrodes and an axial electrode. The function of identifying the direction of acceleration is realized by detecting the closed states of different electrodes. According to the design results of MEMS inertial switch, the dynamic performance of the switch was analyzed by ANSYS software. The results show that the designed switch meets the functional requirements of load direction identification. Based on UV-LIGA multilayer photolithography, the nickel MEMS inertial switch was fabricated on a steel substrate. In the process of fabrication, the line width compensation method was used to reduce the dimensional error caused by swelling phenomenon and removal process of the photoresist. What's more, the thickness compensation method was used to reduce the process error caused by flattening treatment. The overall dimension of the switch is 5300 × 5300 × 270 μm and the smallest line-width is 20 μm. Ultimately, the fabricated switch was tested by the centrifuge device and dropping hammer in XOY plane and Z-axis direction. The dynamic threshold of the switch is between 7.9 and 11.3 g, and the response time in each direction is less than 2 ms. The switch can recognize the direction of acceleration in XOY plane and Z-axis. The switch has an excellent anti-overload performance. Display omitted •A low-g MEMS inertial switch with identifiable load direction was designed.•The function was realized by detecting the closed states of different electrodes.•The switch achieves uniform threshold acceleration in each sensitive direction.•The line width compensation method was proposed to improve fabrication accuracy.•The switch was verified with the centrifugal device and the dropping hammer system.