In this paper, the crude polysaccharides from sugarcane leaves were extracted by mechanical force assisted ultrasonic method. After deproteinization, decolorization and removal of small molecular impurities, the produced crude polysaccharide extracts were purified by DEAE-52 cellulose ion column and DEAE-Sepharose fast flow chromatography to obtain two fractions, SCLP-1 and SCLP-5. The infrared absorption characteristics, antibacterial and antioxidant properties of SCLP-1 and SCLP-5 were further studied, and the results showed that the extraction rate of crude polysaccharides from sugarcane leaves was 1.8%, the protein removal rate was 39.8%, and the decolorization rate was 67.9%; the polysaccharide retention rates of the two processes were 58.6% and 60.2%, respectively, while the polysaccharide retention rate of the process of removing small molecular impurities was 96.8%. Infrared (IR) spectroscopy analysis showed that both SCLP-1 and SCLP-5 exhibited typical absorption peaks of polysaccharides; the results of in vitro antioxidant test showed that the antioxidant activity of SCLP-5 was slightly higher than that of SCLP-1, but lower than V_C; the results of bacteriostasis test showed that both SCLP-1 and SCLP-5 have antibacterial activity against Escherichia coli and Staphylococcus aureus, especially for E. coli.