The principle of capacitive micrometer developed with differential capacitance is systematically introduced and computed through deriving the relationship between input and output.The sinusoidal excitation source using the Direct Digital Synthesis technology is set up in Simulink simulation system.The simulation results shows that amplitude stability and high frequenty stability achieve to 0.000 001 V and 0.000 1 Hz.It is better than past,Moreover,it has increased the precision of marine gravimeter.