Abstract: The effect of the applied electric field on the diffusion activation energy of Cu crystal was studied by the first-principles calculation and current assisted sintering. The results show that the applied electric field and current reduce the difficulty of Cu vacancy generation, but the atomic migration energy is almost unchanged, resulting in a slight decrease in diffusion activation energy after reaching the electric field intensity (current density) threshold (2 V·Å^‒1 (307.1 A·cm^‒2)), and a sharp decrease after exceeding the threshold; finally, after the electric field intensity (current density) reaching 5 V·Å^‒1 (708.5 A·cm^‒2), the vacancy formation energy gradually decreases to 0, the diffusion activation energy drops to the critical value, and the critical value of diffusion activation energy decreases by about 60.2% compared with that of the threshold value. The diffusion activation energy shows a regular decline trend under the action of electric field or current, and the experimental results show a good positive correlation with the first-principle simulation results.