In this paper, a new optical parametric amplification scheme based on electro-optic effect is proposed. The change characteristics of gain bandwidth of potassium deuterium phosphate (DKDP) crystal are theoretically analyzed with the change of deuteration rate, and the variation characteristics of gain bandwidth of DKDP crystal with 70% and 95% deuteration rate under different electric field intensities are studied. At 885 nm central wavelength, the gain bandwidth of DKDP crystal with 70% deuteration rate can be broadened from 90 nm to 124 nm when the electric field strength of 1.67×10 5 V/m is applied. At 808 nm central wavelength, the gain bandwidth of DKDP crystal with 95% deuteration rate can be broadened from 52 nm to 68 nm when the applied electric field is 1×10 5 V/m. The results show that the linear electro-optic effect can effectively broaden the gain bandwidth of the optical parametric amplification system, and the central wavelength of the gain spectrum can be adjusted by electro-optic modulation to achieve continuous wavelength tuning. It has a great application prospect in high-energy ultrashort laser system.