Systemic sclerosis (scleroderma) is a heterogeneous autoimmune disorder characterized by collagen overproduction that leads to cutaneous and internal organs sclerosis and pulmonary arterial hypertension. SSc has high morbidity and mortality. SSc pathogenesis is uncertain. At present most therapies of SSc are symptomatic. Effective therapeutic approaches are lacking. Accompanying a growing understanding of SSc pathogenesis, various key mediators are being evaluated as the therapeutic targets. This review described the effects of these key mediators in SSc.