RNA interference (RNAi) is one of the most importantly protective phenomena forming from the process combating against virus. Since its high efficiency for silencing the expression of proteins at the posttranscriptional level, RNAi shows great prospect in therapeutics for diseases. However, the delivery of siRNA into cells, tissues or organs remains to be a big obstacle for its applications. Many vectors for siRNA delivery have been developed including viral vectors and non-viral vectors, among them non-viral vectors have the advantages of low toxicity, ease of synthesis and low immune response over viral ones. Cationic liposomes and polymer particles, major varieties of non-viral vectors, used for gene delivery, have shown to be suitable for the delivery of siRNA. Based on the concise introduction of RNAi, this article reviews the non-viral delivery systems of siRNA, hoping to provide helpful information for the development of delivery systems of siRNA, and to summarize literatures about siRNA delivery published in recent years.