The utility model discloses a chain tensioning device. The chain tensioning device comprises at least two chain wheel sets, a rack and at least one tensioning mechanism, wherein the tensioning mechanism is arranged between the two chain wheel sets, the two chain wheel sets comprise a fixing shaft and two chain wheels, the two ends of the fixing shaft are respectively fixed to the rack, the two chain wheels are rotationally arranged at the two ends of the fixing shaft in a sleeved mode through bearings, the tensioning mechanism comprises a rotating shaft, an oscillating rod and two tensioning wheels, the rotating shaft is installed on the rack, one end of the oscillating rod is arranged on the rotating shaft in a sleeved mode, the other end of the oscillating rod is rotationally provided with the tensioning wheels, the two tensioning wheels correspond to the two chain wheels respectively, and the tensioning mechanism is kept horizontal through an elastic part and can elastically oscillate up and down. The chain tensioning device is composed of the tensioning mechanism, the rack and the chain wheel sets, the chain tensioning device is simple and compact in structure and convenient to maintain, and time is saved.