The present invention discloses a bicycle rotary crank which comprises a left crank, a right crank and foot pedal holes and middle shaft core holes which are arranged at the cranks. The middle shaft core hole at the right crank is equipped with a sprocket. The invention is characterized in that the bicycle rotary crank is provided with a movable inner core; the outside of the movable inner core is sleeved with an inner core cover; the foot pedal hole is arranged at one end of the movable inner core; the other end of the movable inner core is provided with an inner neck; one end of the inner slot is equipped with a bayonet which is provided with a block position; the inner core sleeve is provided with a neck which can block the block position; the middle shaft core hole is arranged at the outer side of one end of the neck of the inner core sleeve; the middle shaft core holes are arranged at one side of the neck of the inner core sleeve; the lower ends of the middle shaft core holes is integrated with the inner core sleeve as a whole; and the movable inner core arranged between the foot pedal hole and the inner core sleeve is sleeved with a spring. The bicycle rotary crank can ensure that the foot pedal can rotate forwards and backwards and can also rotate axially around the inner core, thus the foot pedal can be folded towards any direction by 360 degrees.