The invention relates to an axial force testing device of a pump impeller and a turbine of a high-power speed-adjusting type hydraulic clutch applied to large mechanical equipment and a testing method. A Babbitt metal is inlaid on a linking plate; a strain gage is arranged in a gap of the Babbitt metal and formed by connecting a terminal, a strain gage out-wire and a strain measuring instrument. The testing method comprises the following steps: testing dynamic strain voltage signals of a leftward sliding thrust bearing or a rightward sliding thrust bearing by the strain measuring instrument under the condition of different filling factors; obtaining dynamic strain values by processing, respectively drawing a variation rule curve according to the dynamic strain values; obtaining the size, the direction and the variation rule of the axial force of the hydraulic clutch, thereby solving the problem that the design of an axial positioning part of the hydraulic clutch is only based on theoretical analysis results which are always difficult to confirm to the actual axial force. The invention provides reliable actual testing data for relevant theoretical researches of the hydraulic clutchand provides basis for the design of the thrust bearings and the selection of friction material.