Porcine circovirus type2 (PCV2) is the major pathogen of weaning multi-systemic wasting syndrome (PMWS), which has caused significant economic losses to the swine industry worldwide. Porcine circovirus type 2 capsid protein（PCV2-Cap）is the main target protein for the preparation of vaccine against weaning multi-systemic wasting syndrome (PMWS). In this study, the recombinant expression and vaccine activity of PCV2-Cap protein in Pichia pastoris were investigated to solve the problems of complex production process and high cost of PCV2 vaccine. After removing the nuclear localization sequence (NLS) from PCV2-Cap gene sequence, a preferential optimization of codon was performed to construct a recombinant expression vector and transformed into the host bacteria (X-33) of P. pastoris. The results of SDS-PAGE and Western blot showed that the Cap protein was successfully expressed in the yeast expression system with a protein size of 26 Ku, and the high density fermentation test in 5 L bioreactor suggested that the concentration of PCV2-Cap protein in fermentation supernatant was 0.53 mg/mL, accounting for 23.5% of the total cell protein. In addition, the animal immunization test demonstrated that Cap protein could stimulate the body to produce specific antibodies. Consequently, the PCV2-Cap gene was secreted and expressed P. pastoris, which might make a contribution to the development of PCV2-Cap subunit vaccines.