Abstract:The chloroplast and PS Ⅱ particles isolated from spinach leaves was treated with sulfite. The results showed that the strength of florescence by PS Ⅱ particle was decreased with increase of both the sulfite concentration and the treatment timer; that the damage was more serious when pH 7.3; that sulfite did not damage young chloroplast but it did so to the aged chloroplast; in which decomposition rate of chlorophyll was slower than that of photoreduction of DCIP; that Ca2+ protected chloroplast from sulfite damage and accelerated the damage of PSⅡ particles; and that the reqular pattern can be described by of Logistic equation.