This article focuses on constant pressure control of offshore refueling tanks, analyzes the characteristics of the tank system in depth, establishes the physical mechanism of constant pressure control through variable frequency speed regulation of electric motors, and explains that adjusting the stator power frequency can change the rotor speed and control the oil pump output to achieve constant pressure. Design a fuzzy PID controller optimized based on the krill swarm algorithm for constant pressure control requirements. Selecting the stator power frequency as the core control variable, using fuzzy reasoning to dynamically adjust the PID gain, and constructing a discrete PID algorithm to update parameters in real time, solving the problem of traditional fuzzy PID parameter tuning relying on experience and difficult to achieve global optimization. By randomly initializing the population, establishing fitness functions, simulating swarm intelligence collaboration and competition, iteratively approaching the optimal parameter combination, the system"s robustness, response speed, and steady-state accuracy are improved. Introducing the krill swarm algorithm in the fuzzy control process for parameter optimization, utilizing its unique Lagrangian model to balance group collaboration and random exploration, adapting to oil flow fluctuations and load disturbances. At the same time, the input values are fuzzified, and fuzzy subsets and quantization functions are designed to finely reflect the complex working conditions at sea; Develop a fuzzy rule table to achieve precise adjustment of gain parameters. Using the weighted average method for defuzzification processing, the fuzzy inference results are converted into actual control signals to achieve constant pressure control of offshore refueling tanks. The experimental results show that the proposed method can achieve the set pressure time in 5 minutes in constant pressure control, with an F1 value of 0.96 and a small fluctuation range. This indicates that the method performs well in dynamic response, steady-state accuracy, and anti-interference ability, effectively improving the constant pressure control effect of offshore refueling tanks.