The paper makes experiment about six T-shaped cross section column frame joints under low periodic cycle loads.  The paper uses variable parameters of beam section height,  the axis-pressed ratio and the volume ratio of hoop reinforcement to research cracks formation and development and the failure mechanism of the joints.  The paper points out that joints'crack shape appears as reverse "K"  but not the common rectangular joints' "X"  shape, and the endure mechanism is inclined to the steep press-pole mechanism.  At the same time,  this paper makes use of a software ANSYS to develop the language APDL two times to T-shaped column joints to carry on nonlinear finite element analysis,  adopts discrete cracking model smeared cracking model,  and carries on the contrast analysis with experiment result.  Analysis enunciates that nonlinear finite element analysis calculation results fit in aill with experiment result.  The paper changes procedure parameters to cause the core area shear-press breakage,  and to do further argument about the formation of the joints crack and the joints failure mechanism.