Objective To analyze the effects of the guideline of community-aquired pneumonia on the achievement ratio of CAP therapy.Methods The data of 417 community-aquired pneumonia patients was analyzed retrospectively.The effect of choosing the first dose antibiotics and CAP guideline on the achievement ratio of CAP therapy was explored.Results(1)The percentage of patients choosing the first dose antibiotic and following Chinese CAP guideline was 68.8%.There was no significant difference in the percentage in five years.(2)There was a statistically significant difference in the failure rate of CAP therapy between the patients who abided by guideline to select antibiotics and the patients who did not abide by guideline(χ2=20.458,P0.001).Conclusion The guideline can decrease the failure rate of firstly selecting antibiotics.