The response mechanism of the pressure fluctuation to the unsteady heat release rate at the ‘unsteady’ combustion state in a strong rotating environment was investigated using a stratified vortex-tube combustor via a large eddy simulation method. Results show that the peak amplitude of heat release fluctuation at the ‘unsteady’ state is just 2.8 × 106 W/m3 and the peak amplitude of pressure fluctuation is always within 3000 Pa based on the vortex-tube configuration, indicating a weak fluctuation degree. The unsteady heat release does not bring about a higher momentum flux fluctuation due to quick momentum damping in the rotating reactive environment. The pressure fluctuation does not relate closely to the momentum flux and its fluctuation; this is due to the effect of the centrifugal force caused by rotating behavior. After splitting the momentum flux into the different components, we found that the tangential component acts in reverse to that of the radial and axial directions in the exterior region. Viz., the pressure increases when the tangential momentum flux increases in the exterior region but decreases when the radial and axial components increase. The laminarization of the fluid suppresses the fluctuations in the radial and axial directions only, therefore the uneven attenuation of the momentum flux fluctuation in different directions is the dominant cause of the enlarged pressure fluctuation in the ‘unsteady’ burning state. Moreover, we find that the pressure fluctuation degree is also closely related to the centrifugal weight coefficient. When this coefficient is far away from zero, the centrifugal effect will become obvious, and vice versa.