The invention relates to a single-yarn control device of a computer type Jacquard warp knitting machine, which comprises an upper yarn guide rod, a weight transmitter, an adjuster and a sliding seat, wherein the sliding seat can move on the upper yarn guide rod; a locking screw is arranged between the sliding seat and the upper yarn guide rod; a sensor of the weight transmitter is fixed on the sliding seat; a sensing roller is fixed on the sensor; the adjuster is provided with a servo motor and a roller bracket which are arranged on the sliding seat, a driving rubber roller connected to the roller bracket, and a floating rubber roller pressed on the driving rubber roller; the driving rubber roller is driven by the servo motor to rotate; and the sliding seat is also provided with a front yarn guide roller and a back yarn guide roller. The device better solves the problem that the connection of the front and the back sheets of a seamless forming product has seams because of the over loose of single yarn; the clearness of a hollow flower shape can be simultaneously guaranteed in knitting meshes, in particular the clear flower type with three-dimensional feeling can be knitted on the Jacquard surface layer of interval Jacquard fabrics with double needles, i.e. sandwich Jacquard fabrics..