A parameter modulation method is proposed to increase the aperture of time lens implemented by electro-optic phase modulation. The implementing principle of this method is theoretically deduced. The effects of modulation parameter Q on the aperture of time lens and pulse compression ratio are discussed for the application of optical pulse compression with time lens. Numerical results illustrate that the proposed method can extend the aperture from 15.6% to more than 50% of whole modulation period and increase the compression ratio from 3.11 to 4.46 for the temporal imaging system with ideal compression ratio of 5 at the modulation frequency of 20 GHz. Besides, modulation voltage in high-frequency temporal imaging system can be reduced by selecting input and output fiber with opposite second order dispersion. The parameter modulation method can effectively improve the aperture of time lens implemented by electro-optic phase modulation and optical pulse compression ratio in temporal imaging system by only adjusting the modulation voltage of electro-optic phase modulation without other components. This method can offer a simple and effective way to improve the performance of time lens based on electro-optic phase modulation.