The invention discloses an MODBUS-RTU bus address conflict detection method, which comprises the following steps: sending data to an MODBUS slave with a specified address, waiting for response of theMODBUS slave, judging whether a response data packet is received or not within a preset time, and entering timeout processing if the data packet is not received; otherwise, entering data packet analysis processing: comparing the received actual data length L1 with the data length L0 which needs to be responded by the known slave equipment, and when L1 is smaller than L0, judging that the data is abnormal; when L1 is equal to L0, judging whether the address code, the function code and the check code are correct or not one by one, if the address code and the function code are correct but the check code is wrong, judging that address conflict exists in the MODBUS slave, and otherwise judging that data is abnormal. According to the method, simple judgment of discarding abnormal data in the prior art is avoided, and the usability and reliability of the MODBUS-RTU bus are improved.