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Gelatin-chitosan nano-SiO2 composite microcapsules were prepared by using paraffin and chitosan as core material and gelatin as shell materials. The influence of microcapsules on the properties and structure was investigated through the adjustment of oil-water ratio and the introdution of nano-SiO2 into chitosan and gelatin, respectively. Microstructures such as microcapsule morphology were characterized by optical microscope and scanning electron microscope (SEM). The results showed that when the ratio of oil to water was 3:1, microcapsules were obtained with better properties and structure. Based on this, different sizes of nano-SiO2 were introduced into chitosan and gelatin, respectively. The results indicated that the microcapsules without nano-SiO2 had spherical structure and some were multi-core microcapsules. The porous structure of the microcapsule wall material appeared and the sphericity decreased when SiO2 was introduced into chitosan or gelatin. With the increase of SiO2 content, the microcapsule shell pore structure and heat loss rate increased. Whether the different size nano-SiO2 was introduced into chitosan or gelatin, the microcapsule heat loss rates increased with the increasing SiO2 content. The thermal loss rates of microcapsules after the introduction of larger size nano-SiO2 were smaller than those of microcapsules with introduction of small size nano-SiO2. [ABSTRACT FROM AUTHOR]