Using density matrix equation, the absorption of the probing field in N-type four-level atomic system with three coupling laser-fields under introducing laser field linewidth is calculated. The results indicate that the coupling-field linewidth abates the atomic coherence in four-level system, which enhances absorption to absorption inhibition and inhibits absorption to absorption enhancement.The coupling-field linewidth leads to decoherence. The results also indicate that the controlling-field linewidth abates the atomic coherence in four-level system, reduces absorption and enhances light transparency in electromagnetically induced transparency. The increase of controlling-field linewidth enhances absorption of the both sides absorption of the spectral line centre in electromagnetically induced absorption, while abates the absorption enhancement of the spectral line centre. So the electromagnetically induced absorption in four-level system switchs to the electromagnetically induced transparency.