The tuffaceous sandstone reservoir is the most important reservoir inWuerxun Sag ofHailar Basin. To strike the water saturation accuracy is very important. There is a great influence on the conduction mechanism of reservoir because of presence of tuffaceous, and then the conductivity can not be fully in accordance with the Archie formula. In the establishment of saturation model to calculate the content of tuffaceous is necessary. The volume model has been established, then by determining the framework parameters of the components, programming is used to strike the volume content of the tuffaceous. Reference the Oshinobu Itoh saturation model, saturation model of tuffaceous sandstone is improved. In the conductivitymodel, the additional conductive of clay can not be ignored, at the same time the existence of tuffaceous rocks increases the conductivity, the resistance of tuffaceous sandstone will be parallel by the resistance of tuffaceous, muddy and the formation water. Actual data processing of the tuffaceous sandstone reservoir has proved the newmodel is much better than the conventional one.