Using the method of homogenous testing design this paper analyses a steel cranebeam with right angle sudden change height near supports of different geomitry parameters by the fi-nite elements.The part of height stress point and the stress con cen tration parameter in the beam arefound.After analysing more element nonlinear regression,the relationship between stress concentra-tion parameter and geomitry parameter is established.This paper also discusses both source ofanalysing result error and effect.