Abstract: Fuzzy implication is the extension of classical logical implication,and the structure and equivalent characterization of fuzzy implication is the current research hotspots.However,fuzzy coimplication,as a dual operator of fuzzy implication is seldom studied.Firstly, (G,N)- coimplication is constructed from grouping functions and fuzzy negation.Secondly,the EP, IP, NP and other properties of (G,N)- coimplication are discussed.Finally,equivalent characterizations of coimplication are given.