The invention discloses a business nature protection method, a device and a system for an electric power monitoring system. The method comprises the following steps: ensuring code security, no virus infection in a process, strong process space isolation and program execution flow conforming to a predetermined track through security check in a compiling stage to protect the security of a business software process; through a data encryption interface of an equipment fingerprint generation secret key, ensuring the storage safety of sensitive data stored in a local machine, and ensuring the communication safety through bidirectional authentication and a mode that a communication processing function cannot execute codes in a landing mode; ensuring the service security in a credible authorization verification mode; and protecting the man-machine interaction security of the service software by fusing unified identity authentication and authorization management of an operating system and a service application user. According to the method, security protection is provided for five essential aspects of process, storage, communication, service and man-machine interaction, so that security protection of the business nature of the power monitoring system is realized.