Disclosed is a flat knitting machine. A grid plate assembly of the flat knitting machine includes: an upper portion cam system in a looping region provided with a looping needle channel D, a loop transfer needle channel C, a loop collection needle channel E and a loop receiving needle channel F. Among the channels, linked emergence and disappearance of a loop transfer cam (18) and a loop collection cam (16, 16') produces function switching. A lower portion cam system is a needle selection region, employs a direct selection/direct jacking working mode, and is provided with two mutually independent needle jack grooves, respectively a looping/loop transfer needle jack groove A and a loop collection/loop receiving needle jack groove B. The needle jack groove A corresponds to a needle selector Aa, and the needle jack groove B corresponds to a needle selector Ba. A selection is made using the needle selector Aa or Ba such that a selected needle selection piece enters the needle jack groove A or the needle jack groove B to participate in jacking, directly pushing a knitting needle to enter a needle guide channel at the upper portion of the grid plate so as to fulfil the corresponding function.