Abstract: The quantum Maxwell-Bloch C-number equations are used to investigate the developing process and coherence properties of electric field and polarization in one dimensional tenuous plasma system in which the homogeneous dephasing damp is exist.The analytic result in linear stage and the numerical result in noulinear stage are shown. Numerical result of the developing process of electric field and polarization and the influenee of stochastic source upon them are given. The coherenee of electric field and polarization and the influence of free electron upon coherence are given too. When ω_pe << ω, the influence of free electron can be negligible.