The invention discloses a crank rocking seat type bicycle which comprises a frame, a front wheel, a rear wheel, handlebars and a rocking seat crankshaft connecting rod mechanism. A fixed saddle is omitted, a movable rocking seat serves as the main power source carrier, the handlebars, pedals (movable type or fixed type) and the frame serve as the pivot, the arm strength, waist strength and leg strength of a rider are fully utilized, the gravity center position of the rider is changed, the rocking seat is driven to move vertically to drive the crankshaft connecting rod mechanism to move, and then the rear wheel of the bicycle is driven to rotate.