Abstract: The migration mechanism of fibers in the twisting triangular space of ring spinning is analyzed by using a new three-dimensional model.It is concluded that the speed of the fiber in the twisting triangular space consists of three vectors components,i.e.the speed along the yarn axis,which is decided by the speed of the front roller,the rotation speed round the yarn axis,which is brought by the twisting effect,and the fiber speed relative to the center of cross-section of the sliver,which is caused by the geometry translation.This theory can serve as a guideline in predicting the movement tendency of fibers and analyzing their migration mechanism in the twist triangular space of ring spinning.