Geophysical prospecting for petroleum exploring and nature disaster forecasting depend on the broadband seismic sensors. Broadband electrochemical seismic sensor has superior performance such as high sensitivity at low frequency and no mechanical noise. These advantages make it widely used in seismology. This paper firstly studied the effect of the elasticity coefficient of the spring on the frequency bandwidth of MEMS based electrochemical broadband vibration sensors in the experimental and theoretical method, indicated that the increasing of the elasticity coefficient of the spring system makes the frequency bandwidth of the sensor more narrow, giving the reference to optimize the seismic sensor in the future work.