Abstract: To solve the problem of thickness non-uniformity of the transmission mode Cs2Te photocathode, the mechanism producing the problem and the influencing factors were analyzed on the basis of theoretical and experimental research. The factors that influence the thickness non-uniformity include the shape of the evaporator, the relative position of the evaporator with the photocathode substrate, the binding energy needed by the Cs/Te atom to complete the mechanical reaction on the photocathode substrate and the temperature uniformity level of the substrate surface before the fabrication of the photocathode. The experiment proves that the last factor has the most important effect on the thickness non-uniformity of the transmission mode Cs2Te photocathode. By changing the heating program, optimizing the warm preservation time and balancing the temperature gradient of the photocathode substrate and pallet, the thickness non-uniformity of the transmission Cs2Te photocathode was improved from 76.4% to less than 10%.