By controlled rolling and cooling process, a Mn-Ti high strength steel with yield strength on the order of 700MPa had been developed successfully. The microstructure consists of fine lath shaped bainite and ferrite. The strengthening factors of this steel are attributed to the tiny interlocked distribution of bainite lath and titanium carbide precipitation. When the amount of bainite is more than 70%, the yield strength of steel is higher than 700MPa, and good mechanical performances are obtained. As a result of presence of finely dispersed bainite slabs the plasticity of steel is improved, with the steel’s elongation being about 19%. Many tiny TiC precipitates are observed under transmission electron micrograph, and these particles result in precipitation strengthening.