Abstract: An improved in-situ solution polymerization method was used in order to prepare the thermoplastic polyurethane (TPU) composite with high mechanical properties, barrier properties and thermal conductivity. Graphene oxide modified by chitosan (CS-GO) was grafted onto TPU prepolymer, then CS-GO/TPU composite was synthesized by chain extension reaction. The microstructure of CS-GO was characterized by FTIR, XRD and FESEM. The properties of CS-GO/TPU composites were tested by universal testing machine, oxygen transmission instrument and thermal conductivity meter. The results show that there is a hydrogen bond between CS and GO, and the dispersibility of CS-GO in the TPU matrix is better than GO. The enhancement of barrier property of CS-GO/TPU composites is due to the uniform dispersion of CS-GO which can effectively block the penetration of oxygen. The interaction between CS-GO and TPU matrix has positive effect on the transmission of stress load and the formation of a thermally conductive network. Compared with the pristine TPU, when mass fraction of the CS-GO is 1wt%, the tensile strength and elongation at break of CS-GO/TPU composites are increased by 106.8% and 111.2%, respectively; the thermal conductivity is 1.55 times higher than the pristine TPU.