Abstract:The negative feedback seismometer transfer function of the feedback model is broken down into low-end and high-end of the frequency characteristics of the two parts. The low-end of the frequency characteristics of the second-order high-pass filter transfer function reveals low-frequency cutoff spreading methods: reduce mechanical natural angular frequency ω0, increase the inertial mass, increase the high frequency end of angular frequency ω0, reduce sensitivity Sv, increase the feedback coil resistance, reduce the diameter of the wire, use higher resistivity material coil, use a weaker magnetic field. We use the negative feedback downhole seismometer experiment to test the low end of its expansion and the theoretical derivation of consistency.