The effects of different solid-solution temperature (500, 600, 700, 800, 900°C) and holding time (0.5, 1, 1.5, 2h) on properties and microstructure of Cu-Zn-Al-Ni alloy were investigated experimentally. The result shows that the hardness of the alloy presents lowest at 700°C and then increases gradually as a function of temperature. It is also revealed that hardness has no relation with the holding time. Phase transition occurs when the temperature is 900°C, as a result of which increases the hardness of the alloy.