In this paper, Al2O3-coated separator with developed porous channels is prepared to improve the electrochemical performance of lithium sulfur batteries. It is demonstrated that the Al2O3-coating layer is quite effective in reducing shuttle effect and enhancing the stability of the sulfur electrode. The initial discharge capacity of the cell with Al2O3-coated separator can reach 967 mAh g−1 at the rate of 0.2C. After 50th charge/discharge cycle, this cell can also deliver a reversible capacity of as high as 593.4 mAh g−1. Significantly, the charge-transfer resistance of the electrode tends to be reducing after using Al2O3-coated separator. The improved cell performance is attributed to the porous architecture of the Al2O3-coating layer, which serves as an ion-conducting skeleton for trapping and depositing dissolved sulfur-containing active materials, as confirmed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS).