The embodiment of the invention discloses a random secret key allocation method and relates to the technical field of safety in order to achieve the purpose that in a node random deploy network, one path secret key is allocated to any two nodes with low energy consumption, and thus the confidentiality of data transmission of the two nodes is guaranteed. The random secret key allocation method includes the steps that deploy parameters are calculated according to a safety strategy of an application scene before the nodes are deployed; a secret key ring is loaded, and the secret key ring is a set of small random secret keys; after the nodes are deployed randomly, the path secret key of a source node (or a destination node) is directly encrypted with a secret key shared with the destination node (or the source node) and transmitted to the destination node (or the source node) through a physically connected path; or after being encrypted through some neighbor node, the path secret key is further transmitted to the destination node (or the source node) through a physically connected path; after the destination node (or the source node) receives encrypted information transmitted by the opposite side, the path secret key is obtained through decryption.