Synchronous belt has such features as exact transmission ratio. non-sliding, constant velocity ratio which can be gained, even motion, absorption of vibration, little noise, the big range of transmission ratio which can nominally reach 0.98, compacting structure, The suitability to multi-axis transmission, no need of lubrication, no pollution and so on. Therefore, the synchronous belts can normally work well in the places where no pollution is allowed and where the working condition is poor and can widely be used in machinery drives, such industrial fields as automobiles, machine tools, textile, chemical engineering, light industry, mining, instruments, oil industry and so on ss well as all kinds of other machinery drive.