Silica nanoparticles and polyethylene-block-poly were doped in sodium acetate trihydrate to in-situ synthesize stelliform nanostructure to enhance the effective specific heat capacity of sodium acetate trihydrate. Sodium dodecyl sulfate and methanol were also used in the synthesis to help the dispersion. A modulated differential scanning calorimeter was employed to characterize the specific heat capacity of pure sodium acetate trihydrate and their nano samples. The measurement was repeated multiple times on different days to confirm the repeatability of the measurement. The result shows the specific heat capacity was enhanced by 11% in comparison with pure sodium acetate trihydrate. The conventional effective specific heat capacity model was compared with the experimental result.