The invention discloses a self-adaptive sun tracking device of a heliostat. The self-adaptive sun tracking device comprises a two-dimension driving reflective mirror, a sunlight tracking sensor, a heat collector and a heliostat base, wherein the reflective mirror, the sunlight tracking sensor and the heat collector are sequentially arranged to form a straight line; the reflective mirror is mounted on the heliostat base through a vertical bar; a tilting rod is fixed on the heliostat towards the heat collector direction; an upright rod locking device is arranged at the tail end of the tilting rod; an upright rod is firmly fixed on the upright rod locking device; the sunlight tracking sensor is fixed at the top end of the upright rod. The self-adaptive sun tracking device disclosed by the invention can be used for self-adaptive precision tracking in real time, is high in response speed, accurate in initial mounting, and quick, simple and easy to adjust, so as to greatly reduce the complexity of the heliostat positioning technology and the construction cost.