To develop micro-alloyed hot rolled low silicon multiphase steels, on the basis of chemical composition design without alternative alloying elements, an investigation has been made of the effect of final cooling temperature on the microstructure and mechanical properties by hot rolling experiment. The results show that multiphase microstructure can be obtained with the final cooling temperature increasing from 420℃to 500℃. The amount of retained austenite increases by 6.5% with the martensite disappearing and a large number of bainites appearing in the structure. When there is a similarity between the rolling process parameters and open cooling temperature, the amount of ferrite and the average grain size of ferrite tend to be the same in the structure, with the final cooling temperature exerting a great influence on the hardness and distribution of retained austenite. When the final cooling temperature reaches 470℃, the hard phase characteristics and the distribution of retained austenite are well matched, with its corresponding yield strength, elongation and the product of strength and elongation being 460 MPa, 31.3% and 21 754 MPa·%, respectively.