Abstract: In the paper, Green function of plates on Winkler foundation with two simply-supported opposite edges and two free edges under unit concentrated bending moment acting at a free edge is derived from Reissner’s plates theory. Based on the fundamental solution presented, the intensity factors of Reissner plates on Winkler foundation with two simply-supported opposite edges and two free edges cracked along symmetrical axis perpendicular to simply-supported edges under uniform load are ob-taind by means of the boundary method. Moreover, the influence of some structural parameters and material constants on intensity factors is analyzed.Calculation shows that the theoretical derivation and numerical results are correct.