The invention relates to a pipe gallery guide wall external formwork, and belongs to the field of pipe gallery construction. The pipe gallery guide wall external formwork is convenient to mount and dismount, the labor cost is lowered, the turnover efficiency is improved, the construction period is shortened, the construction quality is ensured, and a building method of the pipe gallery guide wallexternal formwork is short in formwork filling time. The pipe gallery guide wall external formwork comprises a plurality of steel external formwork units distributed longitudinally and connection parts enabling two adjacent external formwork units to be in butting joint with each other, wherein the connection parts are detachably connected with the external formwork units. A supporting system forsupporting the corresponding external formwork unit is arranged on the outer side of each external formwork unit. A walking system is arranged at the bottom of the outer side of each external formworkunit. According to the pipe gallery external formwork, dismounting and mounting of the pipe gallery guide wall external formwork are facilitated; the phenomena of grout leakage, formwork swelling, water leakage and water seepage are relieved; and the turnover efficiency of the formwork is improved. According to the building method of the pipe gallery guide wall external formwork, the number of construction personnel is reduced, the transferring rate of the external formwork units is improved, and the formwork filling time is shortened.