The invention relates to a coaxial electromagnetic compensating tensioner. The coaxial electromagnetic compensating tensioner solves the problems of poor consistency and uniformity of tension of weft yarn passing through a shed in the prior art. According to the coaxial electromagnetic compensating tensioner, electromagnetic force and spring force are used for jointly controlling clamping force, acting on the yarn, of a ceramic tension clamping piece. By changing the current waveform of an electromagnetic coil, clamping force of a yarn clamping device, which has multiple shifts synchronous with the weaving speed, is outputted for compensating for various wefting insertion characteristics. The coaxial electromagnetic compensating tensioner comprises the ceramic tension clamping piece for adjusting the yarn tension, a plastic bracket, thrust springs, an electromagnet with a controller and an armature. The armature pushes the plastic bracket upwards under the combined action of tensile force of an electromagnetic field of the electromagnet and reactive force of the thrust springs, the plastic bracket transmits the tensile force to the ceramic clamping piece, and therefore the clamping force, acting on the yarn, of the clamping piece is controlled. The coaxial electromagnetic compensating tensioner has the advantages of being high in adjusting fineness, wide in adjusting range, simple in structure, durable, low in price and the like. The tensioner can compensate for the yarn tension under the different wefting insertion conditions, the consistency and uniformity of the tension of the weft yarn passing through the shed can be improved, and the coaxial electromagnetic compensating tensioner has great market demand prospects.