Taking flexural-compressive strength ratio, tensile strength and bonding strength as evaluation indexes, the optimal scheme of mixture ratio of vinyl acetate-ethylene copolymer latex powder (VAE latex powder) modified cement mortar was determined by orthogonal test. Based on the optimal scheme, the effect of VAE latex powder content on mechanical properties and frost resistance of mortar was studied. The results show that the optimum scheme of VAE latex powder modified cement mortar is that the cement-sand ratio is 0.375, the content of VAE latex powder is 10% (mass fraction), and the water-cement ratio is 0.38. VAE latex powder can significantly improve the flexural strength, tensile strength, bonding strength and toughness of mortar. With the increase of VAE latex powder content (8%~12%), the flexural strength, bonding strength and flexural-compressive strength ratio of mortar increase continuously, and the tensile strength decreases continuously, but it is still significantly greater than that of ordinary mortar. The water absorption, mass loss rate and strength loss rate of mortar decrease with the increase of VAE latex powder content. The compressive strength increases first and then decreases with the increase of VAE latex powder content. When the content of VAE latex powder is 12%, the compressive strength of mortar begins to be lower than that of ordinary mortar. Considering the strength and toughness of mortar, the optimum content of VAE latex powder is 8%~10%.