A low alloy and low temperature cast steel containing Cr, Ni and Mo was designed to meet the performance requirements of API 8C for oil rig hoisting equipment. The results show that through the quality control of the casting process and different heat treatment process measures, the structure of the steel after 900 ℃ quenching +650 ℃ tempering heat treatment is typical tempering sorbite, the impact energy of -20 ℃ reaches 90 J, -45 ℃ impact energy reaches 48 J. Under these conditions, the steel shows excellent mechanical properties at room temperature and high impact toughness at low temperature, which meets the material properties required for lifting equipment of oil drilling RIGS.