Green caviar is a high class ingredient in Okinawa, Japan and Philippine. It becomes a new and developing economic aquaculture species in Taiwan in recent years. Previous studies revealed that the polysaccharide extracted from Caulerpa lentillifera is effective in tumor suppression, antioxidation, anticancer, healing hyperglycemia, and preventing cardiovascular disease. In this study, we aimed to utilize the Caulerpa lentillifera cultivated in Penghu to establish related research data for attempting to develop new health care materials and products. The result revealed that Caulerpa lentillifera is rich in plant protein, which is good at anti-oxidation, and unsaturated fatty acid, which is good to health. It could also repress the expression of tyrosinase and nitric oxide. The results of in vitro test showed that the survival rates of HepG2, H1299, Panc-1, HCT116, and HL-60 are efficiently reduced; moreover, the result of fluorescence-activated cell sorting (FACS) revealed that it could also promote the apoptosis in five kinds of cancer cells above, especially HCT116 cells. The bioactive material of Caulerpa lentillifera could be used to develop valued seaweed products. It would be an economic seaweed with high potentail for developing novel and applicable products.