The linear quadratic (LQ)/H∞ control method was proposed for turboshaft engines to reject disturbance.The collective pitch was treated as disturbance during modeling.The state feedback law was obtained based on linear matrix inequality (LMI)

and it satisfied both LQ index and H∞ disturbance rejection index.The disturbance rejection method based on reference adjustment was proposed.The adjustment of power turbine rotor speed reference was achieved by proportional derivative (PD) control according to collective pitch variation

and the overshoot or droop of the real speed was suppressed during maneuver.Simulation results show that the methods proposed can suppress the disturbance effectively and run in realtime.