The calculation theory of stability capacity of steel tube and coupler scaffold is currently an urgent problem to be solved.Based on the analysis of the stability behavior of steel tube and coupler scaffold with X-bracing,a series of simplified model and calculation formulas are put forward.In order to verify the rationality of simplified calculation theory presented,two full-scale tests are carried out.Compared with results from tests,the results from simplified calculation theory is well consistent with it.Therefore,it is concluded that the simplified model and simple formula own a considerable accuracy to forecast the critical load of steel tube and coupler scaffold with X-bracing under uniform load,which offers the reference for relevant researchers and designers.