The most effective sequence of small interfering RNA (siRNA) silencing STAT3 of psoriatic keratinocytes (KCs) was screened out, and the effects of the most effective siRNA combined with ultrasonic irradiation and SonoVue microbubbles on the expression of STAT3 of KCs and the dose- and time-response were investigated. Three chemically-synthetic siRNAs targeting STAT3 carried by Lipofectamine 3000 were transfected into KCs, and the effects on STAT3 expression were detected, then the most effective siRNA was selected for the subsequent experiments. The negative controls of siRNA (siRNA-NC) labeled with Cy3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles were transfected into KCs, then the optimal parameters of ultrasonic irradiation were determined. The most effective siRNA carried by Li-pofectamine 3000 combined with ultrasonic irradiation at the optimal parameters and SonoVue microbubbles was transfected into KCs, and the dose- and time-response of RNA interference was determined. The effect of RNA interference by the most effective siRNA at the optimal time and dose carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles (LUS group) was compared with that only carried by Li-pofectamine 3000 (L group). The results showed that siRNA-3 achieved the highest silencing efficacy. 0.5 W/cm2 and 30 s were selected as the parameters of ultrasonic irradiation. The siRNA-3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles could effectively knock down the STAT3 expression at mRNA and protein levels in dose- and time-dependent manners determined at 100 nmol/L with maximum downregulation on mRNA at 48 h, and on protein at 72 h after transfection. The LUS group achieved the highest silencing efficacy. It was concluded that siRNA-3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles could effectively knock down the STAT3 expression in psoriatic KCs, and the optimized transfection condition and the sequence of siRNA-3 could serve for further research on gene therapy of psoriasis.