Degradable poly(butylene succinate) (PBS) was reinforced with cotton stalk bast fibers (CSBF) which had been pre-treated by the continuous steam explosion method. The non-isothermal crystallization kinetics, crystalline structure and spherulitic morphology of neat PBS and CSBF/PBS composites were investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM). Moreover, the dynamic mechanical thermal properties of neat PBS and CSBF/PBS composites were studied by dynamic mechanical thermal analysis (DMA). The results showed that CSBF played a dual role for acting as both nucleating agents to promote nucleation and physical hindrances to retard the transport of chain segments during the non-isothermal crystallization. In non-isothermal crystallization kinetics, the Ozawa model failed to describe the crystallization behavior of these systems, while Avrami model and Liu model (modified Avrami-Ozawa model) were found applicable. Though the spherulites drastically decreased in size when CSBF were added into PBS matrix, the crystalline structure did not change. In addition, the presence of CSBF largely enhanced the storage modulus of PBS matrix. (C) 2011 Elsevier B.V. All rights reserved.