Abstract: For a ten-nozzle diesel combustor designed for marine gas turbine, experiments were conducted to analyze the effect of fuel staging on its thermoacoustic instability properties by using simultaneous pulsation pressure and image acquisition method and proper orthogonal decomposition (POD) method. Results show that in a diesel multi-nozzle lean premix combustion chamber, the oscillation frequency after opening the pilot nozzle decreases by 11% compared to before opening. Adjusting the fuel staging can suppress the pressure pulsation within the combustion chamber by up to 60%. The oscillation mode is a double limit cycle oscillation with pilot nozzle off, while the oscillation becomes a single limit cycle oscillation with pilot nozzle on. The frequency of the flame heat-release rate oscillation is largely in line with the frequency of pressure oscillation, with the nozzles in the state of thermo-acoustic coupling. The main energy of the oscillations is concentrated in the global axial synchronous oscillation, and there are also circumferential oscillation modes with reduced energy.