To investigate evolution of a Gauss beam and interaction of two Gauss beams in biased centerosymmetric photorefractive materials by applied electric filed, the beam propagation equation is solved numerically with a Gauss beam taken as the input wave.The result shows that a Gauss beam can evolve into steady-state screening bright soliton when the applied electric filed,intensity peak value and beam waist parameters match with the centrosymmetric photorefractive crystal respectively, or it will experience cycles of compression and expansion. It is also found that two same-phase beam attract each other and beams fusions occur at a certain interaction length. While in the case of anti-phase, the two beams repel each other with a force increasing monotonously with the decrease of initial separation.