In order to evaluate the safety and immune effect of subunit vaccines of porcine circovirus type 2（PCV-2）inoculated with needle-free syringes，and to support the application and popularization of needle-free immunization，40 Sanyuan pigs at 3-5 week old were randomly divided into four groups，one group injected at one dose/pig with needle syringes，and other groups with needle-free syringes，that was，1/4 dose/pig，1/2 dose/pig and 1 dose/pig，respectively，all of which were immunized twice on the 1st and 21st days，respectively，the clinical symptoms and body weight of the pigs before and after the test were observed，and the changes of their antibody level and immune efficiency on the 7th，14th，21st，28th and 42nd days were studied. The results showed that no abnormal mental state，diet，drinking water or spontaneous movement was observed after immunization as the pigs react a little due to rapid injection with needle-free syringes；compared with those in the group injected with needle syringes，reduced injection（1/4 dose/pig）could significantly increase the weight gain of piglets（P＜0.05），with same effect as those with needle syringes（P＞0.05）；after immunization with the same dose of subunit vaccines，the antibody level of the pigs in the groups with needle-free syringes was higher（P＜0.01），and the antibody positive rate of all pigs in each group could be effectively maintained until the end of the test. In conclusion，needle-free immunization with subunit vaccines of PCV-2 could be applied and popularized as it was safe with good tolerance and effectiveness，especially reduction injection could provide good protection and improve the growth of piglets.