Abstract: Aimed at the invasion damage of solid phase finely ground particle and liquid in operations of drilling,completion,well killing, and well repair and reservoir bed damage caused by incompatibility among operating fluids,reservoir fluids and mineral,an attacking recessive acid completion fluid for improving reservoir bed was developed.The completion fluid has many advantages such as reduce pH value eliminate organic and inorganic settle screen and temporarily plug,corrode core and improve reservoirs.Results of field test in Bohai QK17-2 oilfield show that the completion blended with chelating acid YXA can improve permeability of cores and increase oilfield productivity.