Tricalcium silicate (Ca3SiO5) bioceramics have good bioactivity and compatibility. In simulated oral fluid they can induce teeth mineralization to repair the acid etched dental enamel. But teeth mineralization effect was relied on particles adhesive ability onto the enamel surface, so a new and simple method was established to evaluate the adherence quantitatively by optical micrograph analyzer and particle counter based on light blocking theory, and further verified Ca3SiO5 particle size affected mineralization effect in stimulated oral fluid (SOF) by nanoindentaion depth. The results indicated that particle size affected the adhesive capability and mineralization ability, in the size of 1-10μm is optimal selection as a toothpaste agent against early caries.