The present invention discloses an alga essence nucleic acid fluid concentration method, to apply the leaching function principle with the operation of freezes defreeze to achieve the goal of extract nucleic acid from the concentrated chlorella. Because of above operation steps with this invention, it will obtain better density of alga nucleic acid fluid. This invention is also to prepare above mentioned particular method of concentrate the alga nucleic acid and produce the alga nucleic acid fluid. The alga nucleic acid fluid may maintain it sweet flavor, and the alga nucleic acid fluid assumes the amber leaning to green color, it is sweet flavor and purely natural taste.