The invention discloses a closed type recycle washing device for a pipeline of a hydraulic system. The closed type recycle washing device comprises an oil washing pipe (1), an oil return pipe (2), a to-be-washed system (16), motors (5) and oil pumps (6); the oil washing pipe (1) is provided with the oil pumps (6) which is driven by the motors (5), the output ends of the oil pumps (6) are sequentially connected with pressure gages (7), a ball valve (8), filters (9), a ball valve (10) and a ball valve (11); the ball valve (11) is connected with one end of the to-be-washed system (16) through oil-resistant rubber hoses (12); the oil return pipe (2) sequentially passes through a ball valve (13), a ball valve (14), the filters (9), the pressure gages (7), an air cooler (15) and a ball valve (3) to be communicated with the input ends of the oil pumps (6); the ball valve (3) and the ball valve (10) are arranged on the side face of the oil washing pipe (1), and the ball valve (14) is arranged on the side face of the oil return pipe (2). The closed type recycle washing device has the advantages that the oil capacity used for washing is saved, the oil washing time is saved, the oil washing efficiency is improved, the on-site arrangement and conveying are convenient, the structure is simple, and the cost is saved.