The embodiment of the invention provides a network link prediction method and device. The method comprises the following steps of: constructing a diffusion network according to the theme number and the network node number input by a user, wherein the diffusion network comprises multiple network nodes and multiple themes; the various network nodes correspond to active vectors and passive vectors; and the active vectors and the passive vectors include parameters to be solved; generating diffusion data according to the active vectors of the various network nodes; obtaining statistical data of the diffusion data diffused in the diffusion network within the pre-set duration; determining parameter values of the parameters to be solved according to the statistical data; and, according to the parameter values of the parameters to be solved, determining the active vector of the first network node and the passive vector of the second network, and determining the network link probability between the first network node and the second network node according to the active vector of the first network node and the passive vector of the second network node. The network link prediction method and device provided by the invention are used for improving the network link predication accuracy.