Six hundred and eight fungi strains were isolated from seventy-eight samples of mangrove plants and soil that collected from Qinglan harbor. Cyctotoxic activity was detected by observing the growth inhibition or killing of the tumor cells under microscope. The result showed that 81 strains (about 13.32% of the total strains isolated) displayed cytotoxic activity against B16 tumor cell. The most fungi strains were isolated from mangrove plant Sonneratia alba, and most of cytotoxic active fungi strains were isolated from mangrove plant Heritiera littoralis.