The permeability of natural gas hydrate-bearing sediments is a crucial parameter for gas production efficiency. A series of models for the relation between the permeability and the hydrate saturation have been proposed, unfortunately, most of these existing models are either too complex or some of their parameters are not clear in physical meaning. This defect seriously limits the practicability and applicability of the existing models. To solve this problem, we proposed an innovative permeability-hydrate saturation model that has only one parameter with clear physical meaning and being readily determined. The proposed model was derived on the basis of the Kozeny-Carman equation by extending the concept of hydraulic radius from two-dimension to three-dimension. This model is evaluated by using experimental data from existing literature, and proved to have a satisfying performance. It could be used for laboratory experiments, numerical simulation and field tests with the premise of known total void ratio.