In this work, a novel nano-sulfur/MWCNTs composite with modified multi-wall carbon nano-tubes (MWCNTs) as sulfur-fixed matrix for Li/S battery is reported. Based on different solubility of sulfur in different solvents, nano-sulfur/MWCNTs composite was prepared by solvents exchange method. The composite was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The modified MWCNTs are considered that not only acts as a conducting material, but also a matrix for sulfur. The electrochemical performance of the nano-sulfur/MWCNTs composite was tested. The results indicated that nano-sulfur/MWCNTs composite had the specific capacity of 1380mAhg−1, 1326mAhg−1 and 1210mAhg−1 in the initial cycle at 100mAg−1, 200mAg−1 and 300mAhg−1 discharge rates respectively, and remained a reversible capacity of 1020mAhg−1, 870mAhg−1 and 810mAhg−1 after 30 cycles. The electrochemical performances confirm that the modified MWCNTs as sulfur-fixed matrix show better ability than any other carbon in cathode of Li/S batteries that had been reported.