Based on micro-nano PIN electro-optic modulator,the effects of carri er concentration on modulation characteristics are analyzed.The average carrier density injected to the i-re gion varying with the time is simulated,and the average carrier density increases with the voltage.A m odulation voltage mode in drive signal with forward and reverse pre-emphasis voltages is used,according to the relationship between carrier average concentration in injected modulation area and time,in order to obtain higher carriers density.This method could not only improve the injected carrier concentration,but also sho rten the extraction time required for reverse carriers.Thus this method could effectively enhance modulation sp eed of the electro-optic modulator.At the same time,the effects of structure parameters on modulation characteri stics are also analyzed.The structure parameters are optimized according to data analysis.Finally,the electro-optic modulator is made with these structure parameters,and static test and optical transient response test of the electro-optic modulator are done.The modulation depth is 11.723dB,and the rat e is 20kHz.