Abstract:By taking the water-base power rod-less oil pumping unit as a research object, based on the theory of fractal box counting dimension, the analysis on property of indicator diagrams was carried out under its 4 different working conditions such as, normal, tubing dropout, fluid insufficient and slow closed of traveling valve, and etc.. The changing property of box counting dimension was studied when the signal to noise ratio (SNR) of pressure-flow indicator diagram was varying in scope of 0.1~0.2%, under different working conditions. The results show that the fractal box counting dimension of pressure flow indicator diagram is little influenced while the system pressure and flow signals’ SNR is reciprocated with the scale of 0.1~0.2%, which indicates that the box counting dimension of pressure-flow indicator diagram can be used to the fault diagnosis of water-base power rod-less oil pumping machine. At the same time, this method is favorable to realize automatic intelligent analysis based on the indicator diagram fault diagnosis. The study result is good to the online fast and accurate diagnosis the operation state of the rod-less oil pumping machine, which has values in practical application and theoretical study values.