Abstract: The data of HAB events in Dapeng bay of Shenzhen from 1980 to 2018 were collected, and the annual and monthly changes of TIN, phosphorus and dissolved silicon in the Yantian waters of Dapeng bay from 1991 to 2018 were analyzed. The results show that the temporal distribution of HABs and the succession of HAB causative organisms are directly related to the change of nutrients. After 2000, the decrease of nitrogen and phosphorus is the main reason for the decrease of HABs frequency; the spring HAB frequency in Dapeng bay is also related to the high nutrient levels in the season. Diatom blooms almost disappeared in Dapeng bay after 2000. The decrease of TIN, phosphorus and dissolved silicon is the main reason for the changes of HAB species composition in the area. Dinoflagellates can adopt various strategies to thrive under conditions of nutrient imbalance, which made it become the dominant HAB species in Dapeng bay.