Aiming at the unstable stability of lower frequency power at present,this paper designs a Signal Generator equipment about 100W, using the method of voltage and current feedback regulation to control the inverter circuit, and adopting LC Series resonance as a filter, producting a stable constant-voltage-constant-frequency(CVCF) Sine wave signal. The equipment passed successfully the test of national center for quality supervision and testing of relay protection and automation equipment, which validates the correctness of academic analysis.