With the rapid development of urban viaduct, an increasing number of curved bridges and irregural ramp bridges are constructed. For the analysis of these structures, the conventional plan link method can not obtain satisfactory results and meet with the engineering accuracy requirement. On the contrary, the special grillage method can solve this issue better. Based on an irregular ramp bridge with Box-girder located in Guangzhou-Shenzhen express way, how to establish FE model by grillage method in Midas/Civil is firstly introduced in this paper, then how to establish 3D block FE model for the validation of grillage model is described. Furthermore, the analysis results of the above mentioned grillage model are presented at the end.