Abstract: During the process of fracture parameters optimization by numerical simulation, the fracture parameters determination, such as half fracture length, conductivity and number of fractures, dependent primarily on the changes of daily output curve or accumulative production curve. We identify the point where the change trend becomes weaker and take the inflection point as the optimal parameters. But the similarity of each change trend at the optimal parameters point, it is difficult to accurately determine which one is the best. Different people lead to different optimal results. After analyzing the rules of curve decline rate, transferring the dynamical production data by introducing the K-value method, optimal fracture parameters could be obtained intuitively. On the basis of curve treated by K value method the optimal parameter range can be determined, which could eliminate errors caused by the human factor.