Abstract: In order to effectively identify and accurately evaluate the gas-layers characterized by low- porosity, low-permeability and developing microcracks. On the base of four-characteristic relations' research and using well-logging data are scaled by core data, methods of direct identification, cross plot, mathematics and comprehensive analyzing are put forward to identify gas-layers qualitatively constrained by geological conditions. Based on research of cracks, quantitative interpretation models of reservoir parameters and identification criterion of gas-layers in different strata are put forward. Since the evaluation method has been put into use, the identification capability and evaluation precision of gas-layers in well-logging are improved, which provides scientific bases for further development of Changqing Gasfield.