According to a synthetical study of the fluid inclusion characteristics of unconventional reservoirs in the Lower Jurassic Da'anzhai limestone from northern Sichuan, it is suggested that the unconventional reservoirs in the limestone be resulted from multiple deep hydrothermal dissolution. The development process of the reservoirs may be divided into three dissolution stages, i. e. the diagenetic stage, tectonic stage and post-tectonic stage, and divided also into five precipitation stages of secondary minerals, i. e. the early-middle diagenetic stage,. late diagenetic stage, early tectonic stage, late tectonic stage and post-tectonic stage. The fluid inclusions in the secondary minerals are well developed, and may be classified into two types, i. e. the inorganic and organic types. The fluid inclusions of the secondary minerals occurring in the five precipitation stages are quite different in respect to their type, shape, abundance, homogenization temperature, salinity, density and composition indicating that the hydrothermal dissolution fluids came from organic and inorganic fluids expulsed from oil provenances in different evolution stages. The relationship between the inclusion genetic characteristics and oil-gas evolution may serve as the indication for the prediction and evaluation of the unconventional reservoirs in the Da'anzhai limestone.