Abstract: In order to research the influence of bacterial cellulose (BC) network structure on crystal and melting process of polylactic acid (PLA), PLA and BC were selected as the matrix and the reinforcement to prepare BC/PLA biological composites with interpenetrating network structure via blending diffusion of PLA-chloroform solution and BC-anhydrous ethanol dispersion. The micro-morphology, spherulite morphology, non-isothermal crystallization kinetics and melting behavior of the composites were investigated by SEM, polarized optical microscopy (POM), DSC and MO's model. The results show that the solution blending diffusion method is available for the preparation of composites with interpenetrating network structure of PLA wound on the surface of BC skeleton. The crystallization temperature, melting temperature and relative crystallinity of BC/PLA composites decrease with the increasing of cooling rate. As a heterogeneous nucleating agent, proper amount BC can improve the crystallization rate and relative crystallinity and refine the spherulite simultaneously. MO's model can describe the non-isothermal crystallization kinetics behavior of BC/PLA composites very well.