Abstract: The new type of Ti-Cr-B HB450 low-alloy abrasion resistant steel was designed on lab conditions. The basic characteristics, microstructure, precipitates and effects of cooling rate on microstructure and mechanical properties of the steel were also investigated. The results showed that the steel has high hardenability, and lots of martensite structure can be found when the cooling rate is higher than 20°C/s. After controlled rolling, quenching at 950°Cand tempering in the range from 250 to 300°C, the fine martensite plus residual austenite can be got with hardness up to HB450 in combination with high toughness, thus meeting the requirements of HB450 ultra-high strength low-alloy abrasion resistant steel. The TEM analyses showed that Ε-carbide particles precipitate in the lath martensite when tempering at 250°C, and these carbide precipitates play a very important role in strengthening the steel.