In the past 20 years, a great number of large and medium-sized oil and gas fields have been discovered in the Bohai Oilfield and the reserve growth rate is quite high. However, in recent years, oil and gas exploration there is faced with difficulties and challenges. The determination of exploration stage is of critical significance to oil and gas exploration. The characteristics and status of reserves growth are different in different exploration stages, and so are the exploration strategies and methods. Upon the basis of previous researches, this paper comprehensively analyzed the number of large and medium-sized oil and gas fields, the degree of oil and gas exploration, the proven rate, the controlled area of exploration wells, and the reserve growth curve and its variation in the Bohai Sea. It is found that the Bohai oilfield is remained in the early stage of an exploration peak. The reserves of Bohai oilfield will still maintain a rapid growth trend in a period. However, the reserves growth in the shallow, middle and deep layers might be quite different in characteristics. In addition to continuously looking for large and medium-sized oilfields, the rolling exploration of surrounding oilfields and subtle reservoirs should be strengthened for the shallow oil and gas fields, which have a relatively high exploration degree and remain in the exploration peak stage, or will enter the late stage of the exploration peak in the near future. However, the exploration degree for middle and deep oil and gas remains relatively low, and is still in the early stage of the exploration peak, the reserves will rapidly increase in the future. They are the main fields to retain the sustainable high-speed growth of reserves in the Bohai oilfields. We should still take large and medium-sized oil and gas fields as the main exploration targets by improving the exploration success rate with new theory and new technology.