Abstract: In order to explore a new method for the red tide monitoring, this study selected one of the typical red tide algae, Alexandrium tamareme, as experimental material.We simulated a complete algal bloom process and examined the important monitoring index (biomass, nutrient concentration), find out the rule of the correlation with stable isotope characteristic value.The results show that algae growth process can be obviously divided into four stages:the adaptation period, the logarithmic growth phase, stable growth phase and decline phase;N, P nutrient concentration decreased with the incubation time, there is a good correlation with the change of biomass in the growth process, but almost no absorption of silicate.In a complete algal bloom process, the stable carbon isotope composition (13C) shows decrease tendency, while the stable nitrogen isotope composition (15N) reveals increase tendency.Therefore, the stable isotope composition can provide new indexes and possible new methods for the red tide monitoring.