During the energy losses of Excavator hydraulic system, the power loss caused by pressure loss in the piping system can not be ignored. Aimed at the 21t hydraulic excavators manufactured by one company, the bucket united hydraulic system was chosen as the study object. The pressure loss in the pipeline was calculated and analyzed through the theoretical derivation, AMESim software simulation and experimental study. The obtained corresponding pressure loss values were 0793, 082 and 083 MPa. Thereby it shows the feasibility of the theoretical study, the validity of the software modeling calculation and the necessity of test study in the study of united hydraulic system pressure loss.