Two-dimensional,ultrathin,robust,and fully π-conjugated organic nanomaterials are highly desirable for application in various fields due to their unique photoelectric characteristics and great number of exposed active sites.However,such matters combining excellent stability,full π-conjugation and adjustability are rare,which has become a bottleneck for their practical application.Herein,we present a novel kind of diyne-linked polymetalloporphyrin nanosheet featuring permanent porosity and full π-conjugation,which exhibits a high-aspect-ratio,outstanding stability and convenient tailoring for electronic structures.Importantly,the novel nanosheets with monodisperse nickel atoms were found to be outstanding heterogeneous catalyst with unprecedented catalytic activity and selectivity for 4-nitrophenol reduction to 4-aminophenol under mild conditions.The findings recommend that diynelinked polymetalloporphyrin nanosheets may offer new platforms for the conversion of photoelectricity and energy in the future.