A multifunctional small dining chair, comprising a front U-shaped support frame , a rear U-shaped support frame , a seat , a backrest , a left armrest , a right armrest and a dining tray , wherein a top of the front U-shaped support frame and a top of the rear U-shaped support frame are arranged in a foldable manner; the seat and the backrest are arranged inside the front U-shaped support frame ; the seat and the front U-shaped support frame are arranged in a foldable manner; a bottom end of the backrest and a rear end of the seat are hinged; a rear end of the left armrest and a rear end of the right armrest are connected to an upper front end of the front U-shaped support frame ; and the dining tray is provided between the left armrest and the right armrest , and the dining tray is rotatable relative to the left armrest or the right armrest ; the dining tray is detachably connected to the left armrest and the right armrest , and characterized in that a bottom of the dining tray is provided with a left inserting rod and a right inserting rod ; a front end of the left armrest is provided with a left rod groove , wherein the left inserting rod is inserted into the left rod groove ; a front end of the right armrest is provided with a right rod groove , wherein the right inserting rod is inserted into the right rod groove ; a front end of the right inserting rod is provided with a disc ; a right bottom end of the dining tray is provided with a disc groove adapted to the disc , and the disc is located in the disc groove ; a right end of the disc groove is open; the disc is open-top and hollow inside; three arc-shaped through grooves are uniformly arranged on a bottom of the disc ; a protruding post is provided at a center of an inner bottom surface of the disc ; the protruding post is provided with a shaft hole being vertically hollow; a bottom cover is provided under the disc ; a top surface of the bottom cover is provided with a lower shaft post and three threaded posts ; an inner top surface of the disc groove is provided with an upper shaft post and three connecting posts ; the lower shaft post is located at a center of the top surface of the bottom cover ; the upper shaft post is located at a center of the inner top surface of the disc groove ; a bottom of the upper shaft post is provided with a first post hole ; a top of the lower shaft post passes through the shaft hole to be located in the first post hole ; a bottom surface of each connecting post of the three connecting posts is provided with a second post hole ; each threaded post of the three threaded posts corresponds to one arc-shaped through groove and one connecting post ; a top of each threaded post passes through an arc-shaped through groove corresponding to each threaded post to be located in a second post hole corresponding to each threaded post ; and each connecting post and each threaded post corresponding to each connecting post are connected by a screw, wherein each of the left inserting rod and the right inserting rod is provided with an elastic clamping button ; a bottom of the elastic clamping button passes through a bottom of each of the left inserting rod and the right inserting rod ; each of a bottom surface of the left armrest and a bottom surface of the right armrest is provided with a clamping button groove ; and the bottom of the elastic clamping button is located in the clamping button groove . <EOS>