The invention relates to a vehicle, in particular to a reciprocating-type stepless speed change bicycle. The reciprocating-type stepless speed change bicycle comprises a frame, a front wheel, a rear wheel, handles and a pedal. The pedal comprises a rotating shaft, treadle arms and treadles. Both sides of the position at the middle part of the frame, which corresponds to the pedal, are provided with a pair of symmetrical traction speed change gears. Each traction speed change gear comprises a tripod and a change wheel arranged at the bottom edge of the tripod. Both sides of a rear wheel hub are provided with a pair of symmetrical chuck clutches. Each chuck clutch comprises a chuck fixed on the rear wheel hub and a coil spring box and a chassis which are connected onto the chunk. The changewheels and the coil spring boxes at the same sides of the frame are connected through pull ropes. The reciprocating-type stepless speed change bicycle has the advantages that 1, the stepless speed change mode is adopted and the reciprocating-type stepless speed change bicycle is economic and simple; 2, a line wheel is adopted to drive and the balance performance is strong; and 3, a special clutchmode is adopted and the reciprocating-type stepless speed change bicycle is free to move backwards.