Through the electro-optic modulation on photons with different polarization modes from quantum dot entanglement sources, the way to eliminate the photon frequency difference is analyzed systematically. We design an electro-optic modulation scheme with Pockels cell, to which a rising or falling voltage of 8 V·ns-1 is applied, thereby realizing a photon frequency shift with a bandwidth of 18 MHz. Simply increasing the modulation voltage slope would realize over 1 GHz frequency shift effectively, which provides a practical basis for realizing the future quantum dot entanglement sources with a perfect certainty.