Batch culture studies on the effects of triphenyltin chloride (TPTC) on photosynthesis, respiration, chlorophyll-a content and carbon, nitrogen, and phosphorus content of Isochrysis galbana cells showed that low levels of triphenyltin (≤1.2 μg/L) promoted the respiration rate, increased chlorophyll-a content and decreased photosynthetic efficiency of chlorophyll-a. Exposed to 1.2 μg/L triphenyltin for 96 h, the cells decreased photosynthetic rate by 8%, increased respiration rate by 27%, increased chlorophyll-a content by 20% and decreased photosynthetic efficiency by 27%. Exposed to 2.4 μg/L triphenyltin for 96 h, the algal cells showed weakening in all of these physiological functions. Triphenyltin decreased the content of carbon, nitrogen and phosphorus in the algal cells. Phosphorus content was the most severely decreased. Exposed to 2.4 μg/L triphenyltin for 96 h,the algal cells’ content of C, N and P decreased by 24%, 34% and 36 %, respectively.