Abstract: This paper reported an investigation on the relationship between cooling rate and relaxation rate of poly(methyl methacrylate)(PMMA) during the micro hot embossing process in a solid-like state. A relaxation-rate-temperature index model was established on the basis of the experimental data of stress relaxation of PMMA at different temperature, and then the relaxation rate and relaxation time constants of PMMA at different temperatures were calculated. A relaxation stress ratecooling rate equation was determined for PMMA in an integral form, which could continuously obtain the relaxation stress rate at different cooling rates. A prism microstructural hot embossing experiment was conduced to verify the practicality of stress rate-cooling rate model through the comparison of the theoretical and experimental results. The results indicated that the relaxation stress rate became smaller with an increase of cooling rate, and the internal stress gained a more sufficient relaxation. This led to a higher molding accuracy for the microstructure.