The uncertainty of fishing schedules makes operation costs uncontrollable, and it is of vital importance to formulate a proper economic decision point. This paper takes a certain fishing well in Bohai Oilfield as an example. Sidetracking from above the fish was necessary without fishing, or from below the casing shoe with fishing. Abandoning fishing or fishing blindly was not the most economical solution. The two concepts i. e., the economic operation period and the decision-making period, were proposed by quantifying the fishing period. Through field fishing attempts, the difficulty of the operation was analyzed during the decision-making period, and it was determined whether the operation can be completed within the economic period; thus minimizing overall operation costs and improving economic benefits of oilfield development. This decision-making method was applied at Well A in Bohai Oilfield, saving a total of nearly 4.2 million. The calculation method for the economic fishing period and the decision-making period proposed in this paper is worthy of promotion.