Abstract: End-tidal carbon dioxide monitoring is an important means of evaluating human lung function and is widely used in clinical emergency treatment, cardiopulmonary resuscitation and other fields. This paper develops a micro-flow end-tidal carbon dioxide monitoring system, which adopts an integrated gas circuit to further reduce the size of the equipment. It uses the method of calculating the RMS value of the differential pressure signal to regulate the gas circuit flow, so that the system can stably operate at a flow state of 30mL/min. In addition, the system realizes system status monitoring and gas parameter compensation by simultaneously detecting multiple environmental parameters such as temperature and pressure. The test results show that the various indicators of the system meet the requirements of relevant standards, laying a good foundation for subsequent engineering.