In Seven flexural members of rectangular steel tubes filled with high strength grouting are experimental studied in order to investigate those mechanical properties.Furthermore, the flexural bearing capacity and stiffness are investigated on condition that the different height——to——breadth ratio and tube thickness, and these results are compared with the criterion g calculate results of Japan AIJ (1997), Europe EC4(1996), China CECSl59：2004(2004)etc.It shows that the criterion Japan AIJ is safest, the criterion DBJ is close to the test and have good economic engineering application and enough safety stock, and the other three criterions lie between the former two.