Abstract: To address the strong nonlinearity, strong time-varying characteristics, geometric boundary variations, and parameter perturbations in pressure regulation of pintle solid rocket motors, a pressure dynamic model considering free-volume variation, nozzle-throat area constraints, and linear ablation was established. Based on equilibrium-point calculation and local linearization analysis, a linear active disturbance rejection control (LADRC) method incorporating equilibrium-displacement feedforward, dynamic incremental compensation, and constraint quantification was proposed, with key control parameters tuned by the differential evolution (DE) algorithm. DE-optimized PID controller (DE-PID) and fixed-parameter PID controller (F-PID) were used for comparison. Results show that LADRC performs well in step tracking, noisy sinusoidal tracking, free-volume variation, and time-varying nozzle-throat ablation, with low overshoot and fast response. Under the tested conditions, the overshoot of the LADRC remains below 0.47%, while the settling time is limited to less than 0.92 s. Its regulation speed is 2.17~6.44 times that of the F-PID. While maintaining an error level comparable to that of the DE-PID, the LADRC provides more stable overshoot suppression, waveform tracking continuity, and disturbance-recovery capability.