The embodiments of the present invention disclose a certificate acquiring method and device. A virtualized network function manager (VNFM) receives a certificate application proxy message sent by a virtualized network function (VNF) instance. The VNFM uses the authentication information to authenticate the VNF instance, and when the authentication succeeds, sends a certificate application message to a certificate authority (CA). Then the VNFM receives a certificate issued by the CA, and sends the certificate to the VNF instance. In this way, through a trusted link between the VNFM and the certificate authority, the instantiated VNF instance applies for a certificate issued by the certificate authority, thereby effectively ensuring security of a management channel between the VNF instance and the VNFM.