Abstract: In Adiabatic Demagnetization Refrigerator （ADR）, PID controllers are commonly used to control the temperature of the salt pill during isothermal magnetization or demagnetization processes. However, due to the strong nonlinearity of ADR systems, traditional PID parameter tuning methods are often ineffective. The practical tuning of PID parameters for ADR systems often relies heavily on trial and error, which is time-consuming and laborious. Genetic algorithms, on the other hand, have low system dependency when tuning PID parameters, which is very suitable for optimizing parameters in complex nonlinear systems. Based on MATLAB software and lumped-parameter approach, a genetic algorithm is applied to PID parameters tuning of GGG salt pill in ADR systems. The results have guiding significance for PID parameter tuning in practical application.