In order to investigate the immunity produced by different inactivated vaccines of mycoplasmal pneumonia of swine（MPS），three kinds of vaccines（A，B and C）were comprehensively evaluated through determination of the indicators including feed conversion ratio，average daily gain，average weight per head when transferring to a new pen，mortality and elimination rate，cough frequency，drug and vaccine cost per head，lung lesion scoring and serum antibody level，etc. 800 one-day-old healthy piglets in large-scale farms were randomly and equably divided into three experimental groups（A，B and C）and one blank control group. The piglets at 7 and 21 day-old in the experimental group，rather than those in the blank control group，were vaccinated according to the vaccine instructions. Blood samples were collected from all pigs at 21，48，80 and 140 days old，and their serum samples were isolated to detect the antibody level against Mycoplasma hyopneumoniae by ELISA. The results showed that the antibody level and positive rate were highest when the pigs were vaccinated with vaccine A. Compared to blank group，the feed conversion ratio of Group A at the stages of nursery and fattening decreased by 10.8% and 13.8% respectively；the average daily gain increased by 19.3% and 7.9%，respectively；the mortality and elimination rate reduced by 2.64% and 1.88%，respectively；cough frequency reduced by 6.38% and 6%，respectively；and the drug and vaccine cost per head reduced by CNY 2.2 and 1.9 per head，indicating the best immune effect and economic benefit. Followed by vaccine B，but vaccine C received poorest effect. In conclusion，the antibody level and immune effect were different when the experimental pigs were vaccinated with different vaccines. Therefore，data support was provided for rational clinical application of i the inactivated MPS vaccines.