A toilet-bowl-locating system for preventing a toilet seat from being deviated left and right of a toilet bowl, the toilet seat having an upper cover and a seat ring, the system comprising locating members and connecting pieces, each locating member being adapted to be installed at a bottom of the seat ring through the respective connecting piece, wherein each locating member comprises a locating seat and a locating piece fixedly arranged on a side of the corresponding locating seat, such that, in use, the locating pieces extend into an interior of the toilet bowl from the bottom of the seat ring downwards and engage with a left limit and/or a right limit of an inner side wall of the toilet bowl; the system further comprising installing seats for connecting with the bottom of the seat ring and corresponding gears for engaging with respective installing seats, each installing seat having an inner perimeter wall therein defining an installing hole for receiving the respective gear and each gear having a connecting-piece-receiving hole for receiving the respective connecting piece, wherein in use, each locating member is adapted to connect to the respective gear via the respective connecting piece, and wherein an internal thread is arranged on the inner side wall of each gear, each connecting piece is a screw, and each screw is adapted to pass through the corresponding locating member to be in screw joint and fixed with the corresponding internal thread of the inner side wall of the corresponding gear; characterised in that each installing seat further comprises internal teeth on the inner perimeter wall and each gear comprises corresponding external teeth on an outer perimeter wall for engaging with the internal teeth of the respective installing seat, such that the connection between each installing seat and the respective gear is rotatably adjustable so as to adjust the position of the locating piece relative to the inner side wall of the toilet bowl without adjustment to the respective connecting piece. a locating seat and a locating piece fixedly arranged on a side of the corresponding locating seat, such that, in use, the locating pieces extend into an interior of the toilet bowl from the bottom of the seat ring downwards and engage with a left limit and/or a right limit of an inner side wall of the toilet bowl; the system further comprising installing seats for connecting with the bottom of the seat ring and corresponding gears for engaging with respective installing seats, each installing seat having an inner perimeter wall therein defining an installing hole for receiving the respective gear and each gear having a connecting-piece-receiving hole for receiving the respective connecting piece, wherein in use, each locating member is adapted to connect to the respective gear via the respective connecting piece, and wherein an internal thread is arranged on the inner side wall of each gear, each connecting piece is a screw, and each screw is adapted to pass through the corresponding locating member to be in screw joint and fixed with the corresponding internal thread of the inner side wall of the corresponding gear; characterised in that each installing seat further comprises internal teeth on the inner perimeter wall and each gear comprises corresponding external teeth on an outer perimeter wall for engaging with the internal teeth of the respective installing seat, such that the connection between each installing seat and the respective gear is rotatably adjustable so as to adjust the position of the locating piece relative to the inner side wall of the toilet bowl without adjustment to the respective connecting piece. installing seats for connecting with the bottom of the seat ring and corresponding gears for engaging with respective installing seats, each installing seat having an inner perimeter wall therein defining an installing hole for receiving the respective gear and each gear having a connecting-piece-receiving hole for receiving the respective connecting piece, wherein in use, each locating member is adapted to connect to the respective gear via the respective connecting piece, and wherein an internal thread is arranged on the inner side wall of each gear, each connecting piece is a screw, and each screw is adapted to pass through the corresponding locating member to be in screw joint and fixed with the corresponding internal thread of the inner side wall of the corresponding gear; characterised in that each installing seat further comprises internal teeth on the inner perimeter wall and each gear comprises corresponding external teeth on an outer perimeter wall for engaging with the internal teeth of the respective installing seat, such that the connection between each installing seat and the respective gear is rotatably adjustable so as to adjust the position of the locating piece relative to the inner side wall of the toilet bowl without adjustment to the respective connecting piece.