Abstract: The mismatch between the time coordination of loop-forming motion and the tufting process can cause problems with unevenness of the tuft pile surface and so results in lower quality carpets.In view of problems above,the key point of the time coordination in the carpet tufting process is proposed firstly,that is used to guide the mechanical design and the phase adjustment of the loop-forming device of the tufting machine.Through Adams motion simulation,specific analysis is focused on the motion time coordination of the conventional loop-forming device which is considered with a shortage in matching the tufting process.Consequently,two methods of the motion time coordination based on non-simple harmonic motion(n-SHM) are proposed to the loop-forming device,which is proved in Adams to well conform to the requirements of the carpet tufting process.And finally the relevant mechanisms are schemed to produce the n-SHM actions of the tufting needle and the looper.