The properties and precipitation behavior of Cu-bearing steels have been investigated. The optical microscope and transition electron microscope were employed to study the influence of interrupted cooling and quenching temperature on the precipitation behavior. Also, the properties of samples with different quench processes were tested. The results show that when the steel is interruptedly cooled and quenched from 650-700°C, with the quenching temperature increasing the volume fraction of martensite becomes larger and the hardness becomes higher. When the microstructure is ferrite the second-phase precipitates occurs and they are proved copper-rich particles. However there are no obvious precipitates in martensite. The copper-rich second phase forms by the way of inter-phase precipitation.