The utility model relates to the technical field of measuring tools, and provides a multifunctional measuring tool for building detection, which comprises an upper connecting piece and a lower connecting piece, a square mounting groove is formed in the lower connecting piece, a first through hole is formed in the inner upper side wall of the square mounting groove, a circular mounting groove is formed in the upper connecting piece, and a second through hole is formed in the lower side wall of the circular mounting groove. A second through opening is formed in the inner lower side wall of the circular mounting groove, a sliding hole is formed in the inner upper side wall of the circular mounting groove, a sliding rod is slidably connected into the sliding hole, a positioning gear is connected to the bottom end of the sliding rod, a connecting rod is connected to the bottom end of the positioning gear, and a square block slidably connected with the square mounting groove is connected to the bottom end of the connecting rod; and a reset spring is arranged between the square block and the inner lower side wall of the square mounting groove, and an inner gear ring meshed with the positioning gear is arranged on the inner side wall of the circular mounting groove, so that when the adjusting angle is too large, the reset spring is prevented from being twisted and deformed, and the purpose of prolonging the service life of equipment is achieved.