Abstract:【Objective】 To study the influence of four kinds of disinfectants mixed with gypsum on surface hardness, compressive strength and flexure strength of three kinds of oral gypsum models. 【Methods】 Metal cylinder mould and silicone impression were made. Four kinds of disinfectants i.e. 2% glutaraldehyde, 0.5% sodium hypochlorite, 0.5% 84 disinfectant and 0.5% trichloroisocyanuric acid were used to mix plaster, dental stone and high strength dental stone; distilled water was used instead of disinfectants for control. Plaster models were then perfused respectively. After disinfection, the surface hardness, compressive strength and flexure strength of the gypsum models were tested and the statistical analyses were made. 【Results】 After disinfection of gypsum with the four kinds of disinfectants, the surface hardness, compressive strength and flexure strength of the three gypsum models had no significant differences from those of the control group (P > 0.05). 【Conclusions】 The disinfection method of mixing the four kinds of disinfectants with gypsum won't affect the surface hardness, compressive strength and flexure strength of oral gypsum models.