Abstract:In order to evaluate technich condition of bridges in forest regions properly,the difference between theory and test value of deflection on reinforced concrete and prestressed concrete beams bridges which are simply supported in forest regions is analysed by authors in this paper.According to test date and the regulation on railway bridges; the limiting values of test deflection are given which are 1/3000 of beam span simply supported to R.C.beams bridge and 1/1600 to P.C.beams bridge.The limiting value can be rigidity standard when supporting test evaluate bridges.