Abstract: Taking ZL114A alloy in QJ3185—2003 《Specifications for Aluminum Alloys ZL205A and ZL114A Castings for Aerospace》 as research object, the effects of the addition amounts of Sb and Te and standing time on the microstructure and mechanical properties of ZL114A alloy in T6 heat treatment state were investigated by experiments. The results show that during the Sb-Te joint modification process, Te can dissolve quickly in molten aluminum and exert its modification role. Due to its high melting point, it takes a long time for Sb to completely dissolve in molten aluminum, and a certain incubation period is needed for the dissolved Sb to fully exert its modification effect. When the contents of Sb and Te are 0.25% and 0.15%, respectively and the standing time is 45 min, the modification effect is optimal, α dendrites and eutectic are uniformly distributed, eutectic silicon is granular, and the mechanical properties of the alloy reach the peak. When the standing time is extended to 90 min, the modification effect does not decline, and the combined modification of Sb-Te has long-term effect.However, when the addition amount of Te is 0.20%, compared with the optimal modification effect, there are fewer eutectic silicon grains, short rod-shaped eutectic silicon becomes longer and thicker, and the mechanical properties of the alloy are reduced.