For higher fabrication costs and poor consistency of electrochemical seismic sensors,a new structure for an electrochemical seismic sensor with planar electrodes based on Micro-electric-mechanical System(MEMS) was presented.A 2D calculation model for the seismic sensor designed was built.The key structure parameters,such as the widths of electrodes,the space between electrodes and the height of the channel which might affect the performance of the seismic sensor,were calculated and optimized by the multi-field coupling numerical simulation method with Comsol software.Through the MEMS surface processes and quasi-LIGA(Lithographie Galvanoformung Abformung) process,the MEMS based electrochemical seismic sensor with planar electrodes was fabricated and packaged.Finally,the characteristic experiments of the frequency response and the tiny-vibration testing for the sensor designed and the traditional seismic sensor based on precise-machining(MET 2003) were carried out.The experiments show that the frequency bandwidth of the sensor designed is expanded from 1 Hz to 30 Hz as compared with that of the MET 2003 and the consistency between the sensor designed and MET 2003 is achieved to 0.887.The noise level is less than 120 dB at 1 Hz.