Abstract: Objective To study the effects of Peris semipinnata 5F on Caspase-3 the enzyme apoptosis correlated of systemic sclerodermaskin fibroblasts and to explore the cause of apoptotic induction of Pteris Semipinnata 5F on Skin Fibroblasts. Methods Change of enzyme activity and protein expression of Caspase-3 was detected by photometric determination and Western blot. Results The result showed that 5F increased the level of Caspase-3 enzyme activity and reduced protein expression with drug concentration increasing. Conclusion 5F increases the level of Caspase-3 enzyme activity and reduces the proenzyme protein expression, which is one mechanism of 5F's inducing the apoptotic of skin fibroblasts.