Abstract: Beginning with study of development and distribution patterns of salt layers, this paper analyzes the influences of salt layers to temperatures and pressures of deep formations, studies the relationship between development of salt layers and the secondary porosity of deep reservoirs in Bonan sag, and predicts porosity of deep reservoirs in the study area. It is believed that porosity of formations up to 5000-6000 m deep may still range between 4. 34% and 6. 44%, which provides large space for deep oil and gas accumulations.