Abstract:The effects of the mixture of Spirulina polysaccharide and Chlorella polysaccharide on antimicrobial and antioxidant bioactivities were studied. Filter paper method was used for detection of antibacterial bioactivities of the polysaccharides compounds，and antioxidant activities of the polysaccharides compounds were assayed by scavenging DPPH free radical and superoxide anionree free radica，etc. The result showed that the polysaccharides compounds had good activities in inhibiting the growth of the strain of Escherichia coli but not in Sarcina lutea when the mixture ratio of Chlorella polysaccharide and Spirulina polysaccharide was 1：4. The polysaccharides compounds showed effective inhibitory action against the selected pathogen Candida Albicans when the mixture ratio was 1：6. The antioxidant activities polysaccharides compounds were he best effects ofDPPH radical-scavenging when the mixture ratio was 1：2. Reducing power of the polysaccharides compounds performed better than the other treatment groups when the mixture ratio was 1：3. Moreoverrides compounds possessed good scavenging activity of lipid peroxidation and hydroxyl free radical-scavenging activity when the mixture ratio of Spirulina polysaccharide and Chlorella polysaccharide was 1：2. Also，the new polysaccharides compounds showed significant superoxide anion-scavenging activity when the mixture ratio was 1：3. Above all，the polysaccharides compounds possessed higher antioxidant capacities than Spirulina polysaccharide or Chlorella polysaccharide and thus could be potential new sources of natural antioxidants for further development and utilization.