The reinforcing mechanisms of inorganic plate-like particulate reinforced polymer composites were discussed based on the micro-mechanical model in this article, and a new expression of tensile strength was derived by introducing an interfacial strength factor. This equation was applied to estimate the tensile strength of inorganic plate-like particulate reinforced polymer composites. The results showed that the relative tensile strength increased nonlinearly with increasing filler volume fraction. Finally, the equation was verified preliminarily using the measured tensile strength of the mica reinforced poly (aryl ether ketone) composites and mica reinforced polydimethylsiloxane networks reported from literature, good agreement was found between the predictions of the relative tensile strength and the experimental data. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers