The invention relates to a knitting machine, in particular to a self-controlled vertical thread adjusting device. The self-controlled vertical thread adjusting device comprises a front plate, a rear plate, a first supporting and positioning block, a second supporting and positioning block, a main circuit board, partition boards, a controller, a yarn clamping and shearing device, a push-and-pull rod and a linkage rod, wherein the first supporting and positioning block and the second supporting and positioning block are respectively installed between the front plate and the rear plate through bolts, the main circuit board is installed at the upper end of the first supporting and positioning block and the upper end of the second supporting and positioning block through bolts, two supporting shafts are installed between the front plate and the rear plate, the two supporting shafts are sleeved with the partition plates arranged at the lower end of the first supporting and positioning block and the lower end of the second supporting and positioning block, the first supporting and positioning block and the second supporting and positioning block form a sealed cavity with the front plate, the rear plate, the main circuit board, the partition boards and the linkage rod, and the controller is arranged in the sealed cavity. The self-controlled vertical thread adjusting device can prevent the controller, a yarn selecting knife and the linkage rod from being stained with oil or stuck by cotton fibers and soft flocks in working, ensures the action accuracy of the controller and improves the stability of textile production.