Using a variational approach, the low intensity photorefractive nonlinear Schr dinger equation is solved. The evolution properties of Guassian beam propagating in photorefractive crystal biased with positive electric field are obtained. The dynamic variation of the beam width spread or compression is investigated by analyzing the potential function description for the variation of beam width. Solutions of the low intensity Guassian beam propagating in the positively biased photorefractive crystal are obtained for the beam width, beam amplitude, and the curvature of wave front. The results show that the amplitude and width of Guassian beam will exhibit a periodical oscillatory or deconcentration behavior when propagating in the positively biased photorefractive crystal. Under certain condition, the Guassian beam can steadily propagate with invariant shape, forming a Guassian soliton. These properties have a high practical value in engineering.