An anesthetic output concentration monitoring device, comprising a first flow sensor located on a side of an anesthetic output device comprising a breathing circuit, a second flow sensor located on a side of an anesthetized object, an anesthetic concentration sensor located on the side of the anesthetized object, a processor, and a memory, wherein the processor is configured to execute a computer program stored in the memory to implement the following steps: monitoring a flow of fresh gas flowing into the breathing circuit by the first flow sensor, thereby correspondingly obtaining a fresh gas flow; monitoring a flow of inhaled gas of the anesthetized object by the second flow sensor, thereby correspondingly obtaining an inhaled gas flow; when the inhaled gas flow is greater than the fresh gas flow, respectively monitoring a concentration of anesthetic in the inhaled gas and an exhaled gas of the anesthetized object by the anesthetic concentration sensor, thereby correspondingly obtaining an inhaled gas anesthetic concentration and an exhaled gas anesthetic concentration; wherein when the inhaled gas flow is greater than the fresh gas flow, the flow of the inhaled gas comprises the flow of the fresh gas and the exhaled gas reflowing into the inspiratory branch; characterized in that, the processor is configured to execute a computer program stored in the memory to further implement the following steps: using the exhaled gas anesthetic concentration and a concentration of carbon dioxide in the exhaled gas to calculate a concentration of anesthetic in the exhaled gas reflowing into an inspiratory branch, thereby obtaining a re-inhaled gas anesthetic concentration; and using the fresh gas flow, the inhaled gas flow, the inhaled gas anesthetic concentration, and the re-inhaled gas anesthetic concentration to calculate a concentration of output anesthetic of the anesthetic output device, thereby obtaining an anesthetic output concentration. monitoring a flow of fresh gas flowing into the breathing circuit by the first flow sensor, thereby correspondingly obtaining a fresh gas flow; monitoring a flow of inhaled gas of the anesthetized object by the second flow sensor, thereby correspondingly obtaining an inhaled gas flow; when the inhaled gas flow is greater than the fresh gas flow, respectively monitoring a concentration of anesthetic in the inhaled gas and an exhaled gas of the anesthetized object by the anesthetic concentration sensor, thereby correspondingly obtaining an inhaled gas anesthetic concentration and an exhaled gas anesthetic concentration; wherein when the inhaled gas flow is greater than the fresh gas flow, the flow of the inhaled gas comprises the flow of the fresh gas and the exhaled gas reflowing into the inspiratory branch; characterized in that, the processor is configured to execute a computer program stored in the memory to further implement the following steps: using the exhaled gas anesthetic concentration and a concentration of carbon dioxide in the exhaled gas to calculate a concentration of anesthetic in the exhaled gas reflowing into an inspiratory branch, thereby obtaining a re-inhaled gas anesthetic concentration; and using the fresh gas flow, the inhaled gas flow, the inhaled gas anesthetic concentration, and the re-inhaled gas anesthetic concentration to calculate a concentration of output anesthetic of the anesthetic output device, thereby obtaining an anesthetic output concentration.