The invention discloses a monitoring information transmission method and a monitoring information transmission system for a nuclear power plant. The transmission method comprises the following steps of receiving a monitoring information access request from a client; judging whether the client has right over access to monitoring information or not according to the access request; if the client is determined to have the right over the access to the monitoring information, calling a hash code to decrypt the monitoring information, wherein the hash code is generated according to a project name and a project password of the nuclear power plant by an asymmetric encryption algorithm; transmitting the decrypted monitoring information to the client. According to the monitoring information transmission method and the monitoring information transmission system for the nuclear power plant, an authorized client can access the monitoring information of the nuclear power plant through the monitoring information transmission system, and an unauthorized client cannot decrypt the encrypted monitoring information even if intercepting information such as an access username, the hash code and the monitoring information through a network, so that the network transmission safety of the monitoring information of the nuclear power plant is greatly enhanced.