Abstract: In the paper,the crack calculating method in RCFEM was modified and the new calculating method of creep suited to the equivalent uniaxial stress-strain relationship is presented. By RCFEM,the propagation of temperature cracks in two cases (with and without sealing block in the elbow section of draft tube in Daxia hydroelectric station) during construction were calculated. Analyzing the causes of cracking and comparing the propagation and width of cracks of these two cases, it is noted that the effect of the sealing block is insignificant and may be canceled.