A micro acceleration switch for long pulse sensitivity was proposed to meet the requirement of a power management system of intelligent weapons for switch latching/unlatching. The switch was designed by using a suspended mass with tooth-shaped structure and a tooth shape guide and the energy dissipation was realized by the mutual collision of the mass and tooth shape guide during the moving process. The switch could implement the unlatch under the high amplitude and narrow pulse width acceleration and the latch under the low amplitude and long pulse width acceleration reliably. The structure and working principle of the switch were introduced. Then, the theoretical analysis and finite element analysis(FEA) of the switch were carried out and its model was simplified. A prototype switch was prepared by UV-LIGA technology, and the functional properties of the switch were verified by the combination of FEA and prototype test. The FEA shows that the switch latches reliably under 3 000 g/3 ms half sine acceleration pulse. The centrifugal test result shows that the static latching threshold of switch is from 2 385.3 g to 2 475.6 g. The dropping shock test and FEA results show that the switch do not latch under 15 000 g/0.3 ms half-sine acceleration. These results demonstrate that the switch meets the design requirements and can be applied to the occasions where the pulse width is required to be distinguished.