Abstract: Several technological processes for improving the power transmission chain's performance and prolonging its operating life are discussed, including carbonitriding of pins and bushings, heat treating of rollers to low-carbon martensite and coldextruding of link plate holes, based on the service conditions of the driving chains of the oil field rigs. Causes of the major failures of the chains are analysed in conjunction with the materials generally used in China in making the chains. Noticeable results have been obtained not only in preventing early failure or wearing of open driving chains but also in increasing the fatigue strength of encased driving chains.