The isothermal crystallization kinetics of PLA and PLA/PBAT/SiO2 composites were investigated by Avrami equation. The results showed that Avrami Indexes(n) of PLA and PLA/PBAT/SiO2 composites were 2.06~2.29 and 1.91~3.05 respectively. The crystallization constant K(T), semi-crystallization time t1/2 and crystallization rateτ1/2 were firstly increased and then decreased with the increasing crystallization temperature. The K(T) and t1/2 of PLA/PBAT/SiO2 composites were higher than those of pure PLA at the same crystallization temperature. Simultaneously, the non-isothermal crystallization kinetics of PLA and PLA/PBAT/SiO2 composites were investigated by Avrami equation with Jeziorny improvement, while n1 values were ranged from 1.31 to 4.88, indicating the coexistence of two-dimensional and three-dimensional growth in crystal growth pattern. The n1, Zc1 and Zc2 of all samples were increased with increasing heating rate, and n1 was less than n2. The result of analysis based on Mo equation was coincident with Avrami equation with Jeziorny improvement, which further indicated that the introduction of nano-SiO2 increased the crystallization rate of PLA. The crystallization activation energy ΔE of PLA/PBAT/SiO2 composites was greater than that of pure PLA, indicating that the introduction of PBAT and nano-SiO2 hindered the migration process of the segment in the main chain of the PLA to the crystal growth on the surface.