The invention provides a voltage acquisition line open-circuit fault detection device and method, and a battery management system. The device comprises N battery equalization circuits, wherein each battery equalization circuit is connected in parallel with one battery; N diagnosis resistors which are installed between each battery equalization circuit and the anode of the corresponding battery; a voltage measurement unit; and a battery management unit in communicating connection with the voltage measurement unit, wherein the battery management unit, according to corresponding battery voltages measured by the voltage measurement unit when the battery equalization circuit corresponding to a to-be-detected voltage acquisition line is connected or disconnected, diagnoses whether the to-be-detected voltage acquisition line is abnormal, such that whether the voltage acquisition line generates an open-circuit fault is effectively diagnosed, the service life of the batteries is prolonged, and the work reliability of the battery management system is improved.