The effects of different heat-shock treatments on biochemical properties and microstructure of Lactobacillus helveticus were determined. The strain was subjected to heat-shock treatment at 67℃ and 70℃, holding time was 10s, 15s and 20s, respectively. The biochemical properties related to cheese ripening such as cell residual viability, lactic acid productivity, and proteolysis activity were monitored. The results suggested that the modified cells using heat-shock parameter of 10s at 70℃, gave the best results upon inhibiting lactic acid productivity and the remaining proteolysis activity. Moreover, SEM photographs showed the changes of surface structure on cell membranes, and elucidated the relationship with heat-shock treatment.