Abstract: Objective：To construct the over RAS1 gene of Candida albicans. Methods：We put the open reading frame of RAS1 gene under the control of MET3 promoter in plasmid pCaEXP to construct recombinant plasmid pCaEXP-RAS1 which can overexpress RAS1 gene. The plasmid pCaEXP-RAS1 was transformed into Escherichia coli DH5α for amplification and extracted by Plasmid Maxi Kit. Then the recombinant plasmid was linearized by cutting of restriction enzyme, and the linear recombinant plasmid was introduced into Candida albicans CAI4 by lithium acetate to select positive colonies on the plates of SD-ura-met-cys selective culture medium. Realtime RT-PCR was used to detect the level of mRNA of RAS1gene. Results：RAS1-over plasmid was exactly established by restriction enzyme digestion. RAS1-over strain was constructed as confirmed by quantitative real-time PCR. RAS1-over strain was selected by quantitative real-time PCR. Conclusions：The RAS1-over strain can be successfully constructed by recombinant pCaEXP-RAS1 plasmid.