The invention discloses a ship-borne weather instrument sensor interface circuit with a simple structure and capable of avoiding misoperation and improving the safety operation of equipment and a method for merging and identifying a connected sensor. According to the technical scheme, the ship-borne weather instrument sensor interface circuit comprises a host interface (1) and a sensor interface (2) and is characterized in that the sensor interface (2) adopts a connector with 7 pin cores, and pins are defined as P1: 5V, P2: 12V, P3: 24V, P4: GND, P5: 485A, P6: 485B, and P7: T, namely connected for detecting. The invention further discloses a method for identifying a connected sensor.