Pressure changes in the flowing fluid result in the growth and collapse of gas bubbles and cavitation, which affects the fluid flowing and pressure. In order to predict gas bubble and cavitation volume change during the pressure pulsations in fluid control system and their effects on the pulsations, a mathematical model of gas bubble and cavitation is studied based on gas bubble resolving and releasing physical processes. The method using genetic algorithms (GAs) in parameter identification for the gas bubble model is presented, including the parameters of initial gas bubble volume, gas resolving time constant and releasing time constant. An example of pressure transients accompanying gas bubble and cavitation inside the hydraulic pipeline is simulated and tested. According to the simulation and experimental results, the feasibility of parameter identification for gas bubble model using GAs is verified.