A ball chain comprises a sequence of balls and an longitudinally elongated spacing chain having a sequence of holes thereon for receiving the balls. The spacing chain further includes a sequence of spacers interposed between the balls whereby the balls will be separated to each other, at least two longitudinally extended flexible strip and a plurality of transverse flexible connecting beam whose two ends respectively are connected to the longitudinal flexible strip, whereby the spacers attach to said connecting beam through an elastic member. The spacers can accordingly deflect and twist freely and the transverse flexible connecting beam can keep as long as possible and provide the best flexibility for being bent in various directions. Therefore, the ball chain can run in a three-dimensionally direction-chain recirculation channel smoothly and with low resistance.