Abstract: A carbene co-grafted modified fabric, a preparation method therefor, and an application thereof. Diazotized cotton fabric is sequentially subjected to a reaction with tert-butyl diazoacetate and octyl diazoacetate to obtain the carbene co-grafted modified fabric; or diazotized cotton fabric is sequentially subjected to a reaction with phenyl diazoacetate and octyl diazoacetate to obtain the carbene co-grafted modified fabric. Taking phenyl diazoacetate and tert-butyl diazoacetate as monomers, co-grafting into a cotton fabric is respectively performed with octyl diazoacetate carbene, a surface structure having low surface energy and good roughened morphology is constructed on a fiber surface, and excellent water repellency is consequently provided.