Abstract: The relations between mechanical properties and microstructures and densities and tempering temperatures of high strength heat treatable GL-90 P/M steel have been tested. After being hardened in controlled atmosphere and tempered at low temperature, P/M steel with the density over 6.90g/cm³ had the structure with fine boundles of strip martensite and the optimum combination of mechanical properties which were similar to Japanese H-90 heat treated P/M steel and had high strengthup to 890MPa and wear resistance being superior to 45^# steel. The inner and outer sleeve irregular shape gears of transmission shaft for JINCHENG motocycle have been successfully made by GL-90 P/M steel.