The invention relates to the automobile component measurement technology field, relates to pipe fitting products applied to pressed-in castings of high precision measurement automobile engine systemsand particularly relates to an auxiliary device for automobile pipe fitting high precision measurement. The auxiliary device comprises three supporting pins, a base seat, ventilation pipes, a precisesleeve and a positioning adjusting block, wherein the center of the base seat is provided with a step through hole, periphery of the base seat is provided with four base seat through holes, peripheryof the precise sleeve is provided with four sleeve through holes, one ventilation pipe can be inserted into one base seat through hole and the corresponding sleeve through hole in a clearance fit mode, and the ventilation pipes stretch into one end of the precise sleeve and are overlapped with an inner wall arc of the precise sleeve. The auxiliary device is advantaged in that on the condition thatmeasurement operation is not influenced, work smoothness in the measurement process can be better guaranteed, operation is convenient, service life can be improved, measurement precision and accuracyare guaranteed, the structure is simple, operation is quite convenient, and strong universality and high measurement accuracy are realized.