Abstract: To study safety performance of plug-in steel-tube scaffold ，it was conducted field test researches on the falsework and the exterior scaffolding for special-shaped structure． Also static and buckling analyses were done by ANSYS finite element software to obtain the stress and stability capacity of scaffolding under different constructing conditions． The results indicate that when exceeds or equals 0. 5，the safety coefficient of ADG plug-in scaffold in French steel structure standard is significantly higher than that in the scaffolding code K = 2 in China; as the nodes of plug-in scaffold are semi-rigid，the theoretical values agree well with the experimental values when stiffness takes 20 kNm/rad． Instability of the falsework belongs to the local instability， the overhang length of vertical bar end has an important impact on the bearing capacity for falsework． It was suggested that the design of plug-in scaffold should use semi-rigid sway frames theory．