Aiming at the problem that the real working load is difficult to obtain in the fatigue analysis of hydraulic excavator working device, a method based on the measuring data and rigid-flexible coupling model was proposed to evaluate the fatigue life of working device. Taking a 21-ton excavator working device as the research object, the actual working pressures and displacements were measured by the pressure and displacement sensors during the digging process for different working mediums. Next, the excavating resistance on the bucket tip was calculated by the mechanical equilibrium equation. The forces of each hinge point was obtained by the rigid-flexible coupling virtual prototype simulation in ADAMS, then the real load-time history of hinge points for multi-working conditions was composed acoording to the proportion of the working mediums. Finally, the fatigue analysis for the boom and bucket rod were conducted in nCode, and the results were compared with that of the fatigue bench test. The results show that there is a good agreement between them. The method proposed in this paper can provide basis for anti-fatigue design of hydraulic excavator working device.