In order to investigate the bending performance of Continuous casting 945 steel sandwich board in cross plate, it is carried out the bending performance numerical simulation for Continuous casting 945steel ,find the largest stress zone in bottom plate when it is at the end of the Elastic stage; Find the most adverse regional、limit bearing capacity、stress-strain relationship and stress three-dimensions degree in the ultimate state. The most unfavorable area of board appeared in middle core board and mid-span junction of sandwich board. When applied 10mm and 90mm displacement, the most adverse regional appeared yield and destruction at first time. According to the stress three -dimensional degree can draw that tension board’s destruction form is stretch destroy in the most adverse regional. When applied limit displacement 90mm, the reaction force is 763.4KN in mid-span. The analysis results note that the most unfavorable area of continuous casting 945 steel sandwich board and destruction form, it has some practical significance for future sandwich board test.