The invention discloses a construction device and method of a pile-head-cutting-free prefabricated square pile. The construction device comprises a pile-head-breaking-free prefabricating machine mold, a pile-head-cutting-free pile feeder and a rubber sealing gasket. The section of the pile-head-cutting-free prefabricating machine mold is in a U-shaped square frame shape, the section width n is the same as the pile diameter of the prefabricated square pile, and the top end and the bottom end of the breaking-free pile head prefabricating machine mold are provided with steel bar fixing steel plates which are each provided with a plurality of through holes used for fixing steel bars; the rubber sealing gasket is used for wrapping the steel bars so as to enable the steel bars to be separated from the breaking-free pile head prefabricating machine mold; and the section of the pile-head-cutting-free pile feeder is in a square frame shape, the section width m is equal to or larger than n+20 mm, and the pile-head-cutting-free pile feeder is internally provided with two diaphragm bracings. According to the construction device and method of the pile-head-cutting-free prefabricated square pile, the process of pile head breaking down is avoided, the prefabricated pile reserving the steel bars is completed, the time and labor cost are greatly saved, efficiency is limitedly improved, and the foundation construction schedule is accelerated.