The invention discloses a stylet motion mechanism of a loop type warp knitting machine. The stylet motion mechanism comprises a stylet, a stylet bed and a transmission main shaft rotatably mounted in an oil tank of the warp knitting machine, wherein the stylet is fixedly mounted at the top end of the stylet bed; a first crank, a first connecting rod, a triangular connecting rod, a second crank and a second connecting rod are also arranged between the transmission main shaft and the stylet bed; the lower end of the first connecting rod is rotatably connected with the first crank; the upper end of the first connecting rod is rotatably connected with the top end of the triangular connecting rod; the left bottom end of the triangular connecting rod is rotatably connected with the second crank; one end of the second connecting rod is rotatably connected with the right bottom end of the triangular connecting rod; the other end of the second connecting rod is rotatably connected with the bottom end of the stylet bed; the first crank and the second crank are driven to rotate by the transmission main shaft; the rotation directions of the first crank and the second crank are opposite; the stylet bed is in slip connection with a rack of the wrap knitting machine. In the stylet motion mechanism disclosed by the invention, the stylet stops for relatively long time in two extreme positions of reciprocating motion, and does not experience impact in motion; the working stability is good, and the manufacturing cost is low.