Abstract: Citrobacter is a conditional pathogen that causes increasing clinical infection cases in recent years. As a result, resistance to commonly used antibiotics (such as -lactam, aminoglycosides and quinolones) in Citrobacter is becoming increasingly prominent. This resistance to -lactam antibiotics is mainly due to the specific -lactamases produced by Citrobacter. Different species of Citrobacter have different sensitivity to antibiotics. Therefore, understanding the resistance mechanism of Citrobacter and the progress is of great significance in the prevention and treatment of infections caused by Citrobacter and control of the spread of drug resistance.