Tandem multi-stanchions and wheels landing gear has three wheels and stanchions, the interaction between wheels and stanchions has large influence on the noise. In order to analyze the influence of wheels and stanchions, based on detached eddy simulation (DES) and acoustic analogy, a simplified landing gear system and its cabin were chosen to study the flow field and aeroacoustic noise. The differences between single wheel and stanchions' flow field and tandem multi-stanchions and wheels' flow field were compared and the directivity of far-field noise was analyzed. The results show the noise spectrum of tandem multi-stanchions and wheels landing gear shows is mainly dominated by broadband noise. The amplitude is affected by vortex shedding of wheels and the interaction of cabin's vortex, and it's mainly dominated by hump-shaped noise source in the mid-to-low frequency range. Cabin noise has both large contributions on the whole noise of two kinds of landing gears. Shear vortex caused by the interaction between wheels and stanchions affects the flow field and destroy the steady vortex of cabin. Besides the noise of cabin can be reduced. Multi-wheels can reduce the turbulent kinetic energy, and change the directivity of the whole structure. In future, noise reduction method of landing gear system should consider the self-noise of rectifier structure, destroy the steady vortex, reduce the flow separation, and reduce the noise generated by flow impact.