The invention discloses a large-tonnage ultrahigh voltage transmission line repair rehearsal system and a large-tonnage ultrahigh voltage transmission line repair rehearsal method. The large-tonnage ultrahigh voltage transmission line repair rehearsal system comprises an animation demonstration chip, a collision detection chip, a parameter calculation chip, an instrument model modeling device, a central processing unit, an environmental model database and a displayer, wherein the data communication ends of the animation demonstration chip, the collision detection chip and the parameter calculation chip are respectively connected with a corresponding data communication end of the central processing unit; the data output ends of the instrument model modeling device and the environmental model database are respectively connected with a corresponding data input end of the central processing unit; the display signal output end of the central processing unit is connected with the display signal input end of the displayer. By the system and the method, the transmission line repairing process is rehearsed, the sizes and the performance of newly developed repair tools are estimated under the condition that tower climbing operation is not required, the frequency of repeatedly testing on a tower is reduced, the manpower and time consumption are reduced and the efficiency is improved.