Air duct in the inlet of the cooling fan is often used in EV (electrical vehicle) due to the usage of AGS (active grille system) and profile. It often leads to the unexpected noise of the cooling fan, the overall level and the BPF (blade pass frequency) noise becomes much worse than before significantly. The experimental results shown that the boundary conditions of the cooling fan affect the noise sensitively. So, the whole engine room CAE model is set up to apply the Computational Fluid Dynamics (CFD) and the Computational Aero Acoustics (CAA). Thus, the CFD and CAA synthesis methods are used to predict the fan noise. After theoretical analysis, it is found that the fan shroud is the most sensitive area which significantly affect the BPF noise. Then different shroud proposals are applied to find the best solutions for the BPF noise, The CAA results shown that the BPF frequency peak of the interior noise reduces 5dB (A) for the best shroud case. Then the best proposal one is manufactured and assembled in EV to validate the effects. The Noise in the EV also cut down in 5-8 dB (A). The Experimental and CAE synthesis method for the whole engine room analysis is confirmed to be useful to solve the cooling FAN BPF noise issue. According to the above researches the cooling FAN NVH design rules are drawn and used in EV NVH design.