The nonlinear differential equation for charge density wave(CDW) proposed by Grüner is analyzed in this paper. According to a periodic solution of the equation suggested in this paper at first, it follows naturally that the sliding of CDW obeys the Ohms law. Many results such as the threshold of starting field and sliding velocity of a single segment are also derived, and the defect of neglecting the first term in the equation is avoided. Applying the result to the model of multiple segments of the CDW, the exponential law of the conductivity and the threshold of applied field, as well as the “narrow-band" noise are obtained simply, which are consistent with the experimental formula. To describe the connection of a multiple segment of CDW system, the mechanism of “elastic connection" is treated as an internal force, which clarifies the vagueness in primary Portis model.