Abstract: This paper is a part of the studies on the mangrove forests in the estuary area of the Jiulongjiang River in Fujian Province. It deals mainly with the accumulation and biological cycle of chlorine in the artificial 20-year-old Kandelia candel community.The main results of the measurements are as follows:1. The amount of chlorine in the standing crop of this community was 3864.13kg·ha-1,in which the amount of the element in the aerial part of the biomass was 1287.75 kg·ha-1 and that of the biomass below ground was 2576.38 kg·ha-1. 2. In the biological cycle of chlorine of this stand, the value of the element in the vegetation uptake was 626.57 kg·ha-1; and that of its return, 27l.31kg·ha-1; and that of its retention 335.26kg·ha-1. 3. The length of the chlorine recycling period is 14 years.