Abstract: In order to meet the need of further reservoir development it is essential to improve the cartographic accuracy of the microfacies map for clastic rock reservoirs, especially to enhance its prediction capability in the cross well area. In the second fault block of the Pubei oil field in Daqing placanticline, the reservoirs and the surrounding rocks of the Putaohua Formation can not be differentiated only according to the acoustic attributes; therefore, a cartographic method which combines the single well facies with the quasi-impedance results is proposed. Firstly, from all the logging attributes, the optimum logging attribute which can differentiate the reservoirs and the surrounding rocks is chosen. A spontaneous potential attribute is chosen in the Putaohua Formation. Secondly, the seismic inversion is processed by using the quasi-impedance logging curve and adding the information of the spontaneous potential curve. Thirdly, the cross well microfacied types can be predicted by the inverted sand thickness; the channel width in the map can be calculated based on the inversion information; and the whole pattern of the microfacies map can be determined on the basis of the quasi-impedance inversion slices. Finally, the microfacies map is completed after the calibration of the single well facies. The real application shows the high accuracy and the practicability of the new mapping method, for the reservoir development and adjustment.