In regard to the poor reservoir development results of the First Member ofthe Kongdian Formation, in the Zilaitun area, Zaoyuan Oilfield, the authors havestudied the rock and mineral characteristics of the reservoir sandstone, its diagen-esis and the influence of diagenesis on the reservoir properties as well as therelations of ulay minerals and reservoir structural models to the potential reser-voir sensitivity and oil bed damage. Based on these,the authors put forward somemeasures to protect oil beds,