The invention provides a dynamometer comprising a power module for outputting an operating voltage required by the dynamometer; an acceleration sensor for acquiring the acceleration of a pumping unitcantilever; a pressure sensor for acquiring the load of the pumping unit cantilever; a micro-control unit connected to the acceleration sensor and the pressure sensor and comprising a an indicator diagram generation module for generating initial indicator diagram data by using the digital acceleration and the load and an indicator diagram compression module for compressing the initial indicator diagram data to generate compressed indicator diagram data by using an indicator diagram data compression method; and a communication module connected to the micro-control unit and used for transmittingthe compressed indicator diagram data. The dynamometer adapts to narrowband wireless network communication.