The hydraulic coupling is a kind of power transmission device combined with pump turbine and casing as its main parts. The purpose of this research is to construct an experimental test set-up and to establish an available soft ware for th characteristics of two domestically developed hydraulic couplings. The test item is torgue rpm. and slip and or efficiency characteristic in accordance with variation of oil quantity. in this case the oil quantity was varied 55%, 67% and 77% of the inside capacity of hydraulic copuling.