The controlled equations based on thermo-chemical non-equilibrium model under the condition of three temperatures were solved numerically by finite difference NND scheme. The inverse bremsstrahlung absorption and plasma resonance absorption were considered when laser transmitted in air plasma. Plasma initiation process was simulated in coupling computation. The mechanism of formation and development of plasma absorbing wave were investigated under different incident laser intensity, while viscidity and diffuseness effects were considered. The results show that the minimum laser intensity needed to form LSD wave based on ZND model is 5.0×10⁶ W/cm² at the initialized temperature 300K and the pressure is 1atm.