Abstract: Optical microscope, transmission electronic microscopy and mechanical tester were employed to analyze the effect of the composition and processing of Ti microalloyed high strength weathering steel on its microstructure and mechanical properties. The results show that Ti addition has a obvious effect on the yield strength of the experimental steel, the grain size remains unchanged as the Ti content increases in 0.05% -0.08%; the increase in strength is dependent on the content of effective titanium that is related to the contents of titanium, nitrogen and sulfur; under the certain content of effective titanium, precipitation strengthening mainly depends on the cooling rate of the experimental steel.