Utilizing pre-cast ECC panels as participating permanent formwork of concrete members,and the validity of using ECC to disperse the single crack in concrete into multiple ones in ECC were studied.In the process,totally two kinds of ECC with different tensile properties,7 series of flat panels with different top surface figures and 3 U-shape panels with different inner surface forms were investigated.To evaluate the performance of the permanent formworks,small ECC-concrete composite beams were cast and tested mechanically.The 4-point bending test results show that the use of pre-cast ECC panels as permanent formwork can significantly improve the load capacity and toughness of a concrete member,effectively dispersing single widely opened crack in concrete into multiple ones in ECC.Most permanent formworks show perfect bond with the concrete cast on them, while the ones with partially debonded zone achieve the best mechanical performance.The U-shape permanent formworks show better performances than the flat ones,achieving much betler improvements in both the load capacity and toughness,together with better crack width control.