Nanochannel conductance measurements are commonly performed to characterize nanofluidic devices Theoretical analysis and experimental investigations imply that the nanochannel conductance does not follow the macro-scale models. It is generally accepted that the conductance of nanochannels deviates from the bulk and trend to a constant value at low concentrations. In this work, we present an improved model for the nanochannel conductance that takes into account the surface chemistry of the nanochannel wall. It figured out that the nanochannel conductance is no longer constant at low concentrations. The model predictions were compared with the experimental measurements and showed a very good agreement between the model and the experiments.