In the past few decades, Nemopilema nomurai underwent blooms over many years that have affected ecosystems in East Asian waters. In the fall, male and female N. nomurai medusa gather to spawn in coastal seawaters. The egg develops into a tiny larva known as planula that swims to the seabed and transforms into the polyp stage. New polyps formed by sexual reproduction replenish the polyp population, and after sexual reproduction, the mature medusa die during the autumn season. The polyps survive in the winter to produce the following year's progeny. Therefore, the number of polyps serves as the basis for medusoid stage (free-swimming) blooms. The Yangtze river's offshore area is a principal breeding location of N. nomurai, where its pelagic stages appear earliest in the Yellow Sea and East China Sea. Additionally, the northern inner coast of the Liaodong Bay (LDB) is another breeding place, and as the season progresses, N. nomurai in this area grow and mature, expanding their area of distribution to the whole LDB or are advected to the southern Liaodong peninsula. In these coastal waters, the spawning of N. nomurai coincides in August-September with the summer monsoon season, where extreme rainfall subject fertilized egg embryo development, planula survival and settlement, new polyp survival and growth. In this study, laboratory experiments were conducted to determine how prolonged exposure to salinity (15, 25, 20, and 30) affected the development of the fertilized egg, settlement of planula, and the development of metamorphosed new polyps. During the embryonic development stage, salinity 20 fertilized eggs developed the highest percentage of planula, where the time to develop planula was synchronized with salinities of 25 and 30. Salinity 15 fertilized eggs were stunted, and their embryo development rate decreased significantly. In the planula settlement stage, planulae showed the highest settlement rates in environments with salinities of 20 and 25. At salinity 15, the larvae's swimming ability in water was significantly reduced, and the larvae developed slowly while the settlement rate decreased significantly. A salinity of 15 significantly increased the planktonic larval duration, however, the settlement time was found to be concentrated 3 or 4 days following culture, which was the same as the other groups. During the settled polyp stage, 4 tentacle polyps after settlement were observed to have the highest survival rate, relative growth rate and specific growth rate in environments with salinities of 20, 25 and 30. At a salinity of 15, the predation ability of the 4 tentacle polyps decreased, and the survival rate, relative growth rate and specific growth rate decreased significantly. This study demonstrates that salinity has a significant effect on the survival and development of the fertilized egg, development and settlement of planula and its survival, as well as the development and growth of the 4 tentacle polyps. In regard to the development and growth of the fertilized egg to the polyp stage, the adaptive range of salinity was found to further increase. Sexual reproduction of N. nomurai occurs in coastal waters, and its sexual reproduction behavior has a certain adaptability to less saline water. Accordingly, when the water is highly saline (20-30), it is more favorable for sexual reproduction. Therefore, high salinity has a positive effect on the supplementation of N. nomurai to the polypoid population via sexual reproduction. However, when salinity in sea environments is too low (15), the development process in the sexual reproduction of N. nomurai is slowed, reducing the development rate and adversely affecting the supplementation of sexual reproduction to the polyp population.