The correlation between K + -Na + diffusion coefficient and mechanical properties of chemically tempered and hybrid tempered (chemically tempered subsequent to thermally tempered) aluminosilicate glass are investigated. Firstly, the potassium ion concentration profiles are experimentally measured and the diffusion coefficient is calculated according to the Boltzmann-Matano approach. Secondly, the flexure strength and Weibull modulus are determined using a combined experimental (coaxial double ring) and finite element analysis method. The results indicate that the flexural strength decreases with the diffusion coefficient of the air side for both types of glass samples while there is no significant relationship between diffusion coefficient and Weibull modulus. Diffusion coefficient on air side shows a higher value than that of the tin side. With the same diffusion coefficient, the flexural strength of chemically tempered glasses are found to be higher than that for hybrid tempered glasses. The effect of diffusion coefficient on modulus of rupture (MOR) for hybrid tempered glass is more remarkable. These results would be useful in designing the strength of glass and guiding the strengthening process by chemical or hybrid tempering.