Abstract: It has been identified both theoretically and practically that semilog relationship of well test curves in low permeability gas reservoir is characteristic of bending upward with a concave shape and that causes resulting in a nomaly of well test curves in low permeability gas reservoir are effect of wellbore afterflow and existence of skin effect as well as extremely low reservoir permeability. Present methods of conventional well test interpretation and modern well testing analysis are all not applicable in this case due to the anomaly of the well test curves. This paper suggests a method of combining optimisation method and anumerical simulation to interpret this type of curves. The analysis of data from many field measured wells shows that this method is feasible.