A conduction channel model is proposed to explain the high conductivity property of nc-Si: H. Detailed energy band diagram is developed based on the analysis and calculation, and the conductivity of the nc-Si: H was then analysed on the basis of energy band theory. It is assumed that the conductivity of the nc-Si: H stems from two parts: the conductance of the interface, where the transport mechanism is identified as a thermal-assisted tunnelling process, and the conductance along the channel around the grain, which mainly determined the high conductivity of the nc -Si: H. The conductivity of nc - Si: H is calculated and compared with the experiment data. The theory is in agreement with the experiment. A conduction channel model is proposed to explain the high conductivity property of nc-Si: H. Detailed energy band diagram is developed based on the analysis and calculation, and the conductivity of the nc-Si: H was then analyzed on the basis of energy band theory. It is assumed that the conductivity of the nc-Si: H stem from two parts: the conductance of the interface, where the transport mechanism is identified as a thermal-assisted tunneling process, and the conductance along the channel around the grain , which mainly determined the high conductivity of the nc -Si: H. The conductivity of nc - Si: H is calculated and compared with the experiment data. The theory is in agreement with the experiment.