Using cationic liposome as a carrier to deliver a complex of protamine and STAT3 siRNA, and through a series of in vitro experiments, we confirmed that the complex system could significantly inhibit the expression of STAT3 in melanoma cells B16 and promote the apoptosis of tumor cells. First, a series of characterization tests were conducted on the carrier material, and the particle size and potential of the carriers and siRNA complexes of different composite ratio were detected. Subsequently, B16 cells were transfected with the carrier and siRNA complex and the transfection efficiency was determined, then the toxicity of the composite was tested. In addition, a series of experiments such as apoptosis, plate cloning, real-time PCR and Western Blot were performed to further determine the effectiveness of the carrier complex. The results showed that cationic liposome carrying STAT3 siRNA with protamine showed good targeted therapeutic performance and excellent delivery efficiency, and the composite system maintained good stability and low toxicity.