The efficiency of thermodynamic cycles can be improved by using the optimized working fluid. In the present paper, classic molecular dynamics simulations and grand canonical Monte Carlo were employed to examine the thermal energy storage characteristicsof R125/UIO-66 and R125/MOF-5 nanofluids. The results indicate that the adsorption of R125 in MOF-5 is larger than that in UIO-66. Also, the thermal energy storage capacity of R125 was strengthened by mixing with UIO-66 or MOF-5 nanoparticles. In addition, the R125/UIO-66 mixtures can store less energy than that of R125/MOF-5 mixtures except the temperature difference is 30 K to 50 K.