Abstract: The effects of cold rolling deformation on the microstructure and mechanical properties of quenched 10 steel were studied by means of SEM, hardness test and tensile property test. The results show that the microstructure of quenched 10 steel is lath martensite with random orientation. Within the range of 10%-76%, with the increases of deformation, the martensite in the microstructure of 10 steel tends to arrange in the rolling direction, and it is continuously elongated along the rolling direction, and the grain is gradually refined. With the increases of deformation, the hardness and strength of 10 steel increases gradually, the elongation and impact toughness decrease gradually. Cold rolling deformation is a suitable strengthening method for 10 steel. The hardness, tensile strength and yield strength of 10 steel with 52% deformation reach 479 HV, 1734 MPa and 1588 MPa, respectively.