Abstract: Sodium Acetate Trihydrate (SAT) has some problems in the field of solar photo thermal conversion, such as super- cooling, phase separation, uncontrollable energy release, poor thermal conductivity and easy leakage. In this paper, banana nano-cellulose/montmorillonite aerogel (CM) with porous structure was prepared with banana nano-cellulose and montmorillonite as raw materials. SAT was modified by acetic acid and water, and the modified SAT was loaded in CM based on vacuum impregnation, to prepare banana nano-cellulose/montmorillonite @SAT composite phase change material (CMS) with latent heat storage and controlled energy release. The results show that adding 10% acetic acid and water can make SAT stable super-cooling and improve phase separation. The loading rate of CM is as high as 2615%, which makes CMS have excellent dimensional stability and leakage resistance. The thermal conductivity of CMS is 0.61 W/(m·K), which is more than 74.3% higher than that of pure SAT. After 50 heating cycles, the melting enthalpy shows only a slight change, which shows that CMS has excellent heat storage capacity and cycle stability. Under the illumination of 150mW/cm², the maximum temperature can reach 80.2℃. Using Type T thermocouple as heterogeneous interface stimulation to induce crystallization exothermic, CMS quickly releases latent heat to heat up, and the total exothermic time of only 10 g CMS can reach 130 min; It shows that CMS has excellent latent heat energy storage and controllable energy release ability. CMS has increased more possibilities for the practical application of composite phase change materials in the field of solar photo thermal conversion.