The paper reviews the eastward strategic shift of China's oil exploration in 1950s and the discovery of Daging Oilfield. The joint efforts by the former Ministry of Petroleum, the former Ministry of Geology and the Chinese Academy of Science are described. Also described are the contributions by Mr. Li Siguang in giving advice to the Central Government for decision - making, the former Ministry of Geology in providing geophysical and geological data, and the former Ministry of petroleum in conducting comprehensive research and organizing and accomplishing such work as deep - well drilling, coring, formation test evaluation, etc. The paper sums up the basic experience in oil exploration in 1950s aiming at to provide references for geological prospecting of minerals in the new century.