The utility model relates to a transformer on -load tap -changer alternating current -direct current parameter testing appearance. Its purpose is in order to provide a simple structure, transformer on -load tap -changer testing arrangement that detection?accuracy is high. The utility model discloses a power switching circuit, direct current detection circuitry, voltage acquisition circuit, electric current acquisition circuit and central processing unit. Power switching circuit and direct current detection circuitry's input inserts the power respectively, and direct current detection circuitry's signal output part is connected with central processing unit's signal reception end, and power switching circuit's output is connected with voltage acquisition circuit and electric current acquisition circuit's signal acquisition end respectively, and the signal reception that voltage acquisition circuit and electric current acquisition circuit's signal output part passes through AD detection circuitry 3 and central processing unit holds and is connected. Central processing unit's data output end is connected with the data input of touch -control display screen end, and central processing unit's control end is connected with the control signal output of touch -control display screen.