The article presents the influence of the deformation process on the microstructure and mechanical properties of low carbon alloy steel which heat treatment by TBF processing. When the samples are deformed at different levels: 20, 40, and 80%. The research results show that when the sample was deformed with the 80%, the highest strength was 800 MPa, the highest elongation was 36%, the product between the strength and the elongation (Rm*A) was the highest, 28774 MPa*%. This alloy deformed at a level of 80%, the content of austenite in this microstructure of this alloy was the highest about 16%. The content of ferrite was 52% with the average particle size of ferrite was 6.4 μm, the particle of residual austenite was 2 μm. The results of the microstructure have contributed to improving the mechanical properties of steel. The phase which was improved the mechanical properties of this alloy had grain size and dispersed.