The effect of ultrasonic vibration temperature on the microstructure, morphology of eutectic phase and mechanical properties of vacuum counter-pressure casting aluminum alloy were investigated using OM, SEM and electronic universal tester. The results show that the effect of ultrasonic vibration temperature on the microstructure and mechanical properties of aluminum alloy is significantly affected under synergistic action between ultrasonic vibration and vacuum counter-pressure. The microstructure of the primary phase is obviously refined with the increase of the ultrasonic vibration temperature, the optimum ultrasonic vibration temperature is 720℃, the primary phase of the alloy is changed from the part of the dendrite or rosette crystals into fine equiaxed grains, the morphology of eutectic silicon can be changed from thick needle-plate like to fibrous. Meanwhile, the tensile strength and elongation of aluminum alloy reach the maximum value, which are 326.96Mpa and 5.57% respectively. the tensile strength and elongation of aluminum alloy with compound treatment compared with the aluminum alloy in ultrasonic gravity casting increase by up to 14.49%and 22.15% respectively and they are increase by up to 6.33% and 8.16% respectively compared with vacuum counter-pressure casting aluminum alloy.