a pneumatic splicing apparatus for spun yarns comprising a splicing member having a splicing hole and a jet nozzle for jetting a compressed fluid into the splicing hole , control nozzles arranged on both the outer sides of the splicing hole to suck and to untwist the yarn ends , cutting devices for cutting the yarn ends , and yarn guiding means for inserting the yarn ends into the splicing hole . the control nozzles provides with a cylindrical sleeve slidably fitted in the nozzle hole thereof to change the position of a jet hole of the control nozzle relative to the yarn ends to be untwisted .