Abstract: Experimental research and theoretic analysis show that the webs of some joints with specially shaped columns exhibit severe failure under low cyclic loading,so the joint with specially shaped columns become the weak part of structures with specially shape columns,and it restricts the storey height of this structure.Based on the low cyclic loading of a exterior joint with specially shaped columns reinforced by polypropylene fiber at the core of the joint and a joint with specially shaped columns not reinforced,it is compared the failure characteristic,the bearing capacity and ductility,the hysteresis curve of the moment-rotation at end of beams of the two specimens;it is studied the change of the stirrup strain of the core of joints,and is also analyzed the cumulated damages with the damage estimating model.It is shown that fiber reinforced concrete could improve the failure characteristic and enhance the cracking load effectively of the joint with specially shaped columns,so the joint is never the weak part of structures with specially shape columns.