Abstract: In this work trimethylaurylsodium sulfate(TLS) was used as a novel reagent for extraction of total cellular nucleic acids from the cyanobacterium, Anabaena azollae. It is found that TLS can replace Triton X-100 and proteinase K, but can not take the place of Sarkosyl in standard method. Compared with the standard method, the productivity of total nucleic acids from the cells was 98.9%, 103.8% and 47.3% respectively, When TLS replaced Triton X-100, proteinase K or Sarkosyl. The effect of TLS varied with the growth phase of the cyanobacterium. The test of restriction endonuclease digestion by EcoR I indicated that DNA extracted and purified by the method of TLS replacing proteinase K was sensitive to cleavage. After treated with lysozyme, the filaments broke down into singular cells. Then after treated with TLS, the debris of broken cells were observed under an optical microscope. Also scale-like degradation and perforation were found on the wrinkled cell surface of Anabaena azollae from observations using SEM.