The invention discloses an overwater self-elevating type pile-top-movable pile driving platform and a construction method thereof. The pile driving platform comprises a self-elevating type overwater platform body, at least two guide beams and at least four ejecting pushing devices; the self-elevating type overwater platform body comprises a moon pool; the at least two guide beams are separately and detachably arranged on the sides of an operating platform and below the moon pool; each ejecting pushing device comprises a large sliding plate, a small sliding plate arranged on the large sliding plate, supporting structures, a vertical jack fixed on the small sliding plate, a transverse jack fixed on the small sliding plate and longitudinal jacks fixed on the large sliding plate, the supporting head of the telescopic end of the transverse jack is fixed to a cylinder block of the vertical jack; and the supporting heads of the telescopic ends of the longitudinal jacks are fixed to the smallsliding plate. With the platform, the problems that pile driving barges are difficulty in pile sinking, the construction precision is poor, the self-elevating type overwater platform moves and is positioned frequently and the like under bad hydrologic conditions such as deep water, rushing water, big waves and the like are solved, and the engineering requirements for accurate positioning, low cost, high construction efficiency and the like are met.