Effective hardening depth (EHD) and surface hardness (SH) achieved by carburizing heat treatment play vital roles in guaranteeing the fatigue performance of heavy load carburized gears, which are often subjected to fatigue failure in the engineering practice. In this study, a strategy of combining the pre-shot peening process and subsequent carburizing heat treatment was proposed to improve the efficiency of carburizing heat treatment of AISI 9310 gear steel. Characterizations of hardness, material microstructure, surface roughness and micro-strain of treated roller samples were conducted with helps of a microhardness tester, optical microscopy, scanning electron microscope, white light interferometer and X-ray diffraction, respectively. The underlying mechanism was explored in terms of discovering the relationship between EHD and microstructure, plastic deformation, surface roughness. Results indicated that the efficiency of carburization heat treatment of AISI 9310 gear steel has bee