The invention provides a window cleaner with an adjustable potentiometer. The window cleaner comprises a main body, a control device and a boundary detection unit, and is characterized in that the boundary detection unit comprises an action part, a spring element, a limiting part, a connecting rod and the adjustable potentiometer; the main body is provided with a detection surface, a limiting surface and a guide hole; the guide hole is located between the detection surface and the limiting surface, and the central axis of the guide hole is vertical to the detection surface; the spring element sleeves the action part, one end of the spring element is abutted against the action part, and the other end of the spring element is abutted against the guide hole; the limiting part is arranged at the action part; the elastic force of the spring element can drive the action part to move and protrude out of the detection surface, until the limiting part is clung to the limiting surface; the adjustable potentiometer is arranged at the main body, and is connected with the control unit. The window cleaner has the beneficial effect that whether a glass boundary is reached, the depth and width of a gap are judged by detecting voltages of two ends of the adjustable potentiometer and comparing the voltages, and the safety is improved.