The effects of ultraviolet (UV) radiation and low salt stress on the growth of Enteromorpha pwlifera thalli were investigated in this paper. The results showed that UV radiation could inhibit the growth of E. pwlifera, with the thalli experiencing negative growth, and such inhibition was higher at the salinity of 24 than at the salinity of 12. After high intensity of UV exposure, the frond became thinning, soft, scattered, and some cell damages were observed under microscope, with the contents spilling after death. While low intensity of UV exposure had little effect on the growth rate. Four groups of salinities, 0, 6, 12, 24 were set in this experiment, and the experiment lasted for 42 days. During the early 21 days, the salinity of 0 showed no significant effects on the growth, with less changes of plant color. But with the culture time extending, the algae became soft and loose, and the plants appeared yellow and then white until death. The plants at other salinities were normal, indicating that the frond of E. pwlifera had a certain tolerance to low salinity stress, but it could not tolerate to low salinity stress for a long time.
