Embodiments of the present invention provide a network service instantiation method and device, so as to solve the problem of a VNF instance failing to not only serve another NS and but also meet requirements of this NS in the prior art. The method comprises: a first device receives a network service (NS) instantiation request sent by a second device, the NS instantiation request being used for instructing the first device to perform an NS instantiation process, the NS instantiation request comprising modification information for performing modification of at least one virtualized network function (VNF) instance, the first device being a management entity for performing the NS instantiation, the second device being an entity for initiating the NS instantiation, and the at least one VNF instance being at least one that is needed by the NS among VNF instances created in a network framework; and the first device modifies the at least one VNF instance according to the modification information.