Abstract: Research on acid fluid flowing reaction in fracture is very important to fracturing design. The 2-D simulation models of acid fluid flowing reaction is usually supposed that the widths of fracture is a const, and using mass transfer coefficient make it change to 1-D models, this reduces the precision of simulation results. Based on material conservation theory, a new acid fluid flowing reaction simulation model was established, using difference and LU method along changed fracture’s widths and lengths will be calculated. Applications indicate that the new model can reflect reactions of acid fluid in fracture more adequately.