Jellyfish envenomation is a world-wide health problem, which often seriously affect the fishery and bathing activities. To date, few individual jellyfish venoms proteins have been thoroughly characterized yet. In this work, four species of scyphozoan jellyfish (Nemopilema nomurai, Cyanea nozakii, Aurellia aurita and Rhopilema esculentum) are compared according to their, cytotoxicity, hemolytic potency, brine shrimp toxicity and protein components. Jellyfish venoms showed higher cytotoxicity in H9C2 heart myoblast than in C2C12 skeletal myoblast, with the exception of C. nozakii venom. This result suggests that the selective cytotoxic effects may be possibly related to their in vivo effects of cardiac tissue dysfunction. On the other hand, hemolytic activity could be also observed from all tested jellyfish venoms. N. nomurai jellyfish venom displaying the greatest hemolytic activity. As an alternative method of evaluating the toxicities of jellyfish venoms, the toxicity on brine shrimp was examined with the four jellyfish venoms. From this, the venom of N. nomurai showed higher toxicity against brine shrimp than the other jellyfish venoms, which is consistent with the results of cytotoxicity assay as well as hemolysis assay of the present study. SDS-PAGE analysis of four jellyfish venoms showed the similar pattern with molecular weight of around 40 kDa, and appeared to be the major protein components. These results provided that N. nomurai jellyfish venom was potently toxic than other scyphozoan jellyfish venoms and may explain to some extent the deleterious effects associated with human envenoming.