An elevator balance coefficient detection method includes the following steps: (1) connecting an electrical energy detection device to a power line of an elevator driving motor, and connecting a speed detection device to a mechanical transmission member of an elevator car; (2) measuring and recording in real time the car speed data and driving motor power data when the car and a counterweight move to a same horizontal location; and (3) based on above detection data and basic parameters of the elevator to be tested, and according to transmission relationship between the elevator's operating condition and energy during operation, calculating and obtaining the value of the balance coefficient. A corresponding device includes an elevator data acquiring system and a detection data processing system. The elevator electrical energy detection device is an AC broadband power measuring device. The elevator speed measuring device is a steel rope displacement measuring device employing a photoelectric mouse chip circuit component or a tachometer type speed measuring device. The invention has the advantages of quick measuring and high accuracy of measuring.