Abstract: This article deals with various diagenesis which are closely related to the development of pores in the Jurassic-Cretaceous sandstone reservoirs. Through the analysis on a large number of cast thin-sections of cores in the Hailaer Basin and many measurements of cath-doluminence, electronic micro-probe, SEM EDX, isotope etc., the criteria for the recognition of diagenesis caused by meteoric water apd freshwater have been discussed in this paper. Furthermore, the diagenetic sequences are reconstructed in the terms of differentiated diagenesis patterns. Therefore, it is the both theoretic and practical significance to study the burial history of basins, the evolution of pores and reservoir development.