Impedance inversion is an important method in processing seismic lithologic inversion. The key of the inversion lies in the demarcation of the high-precision reflection coefficient amplitude and the acquisition of high-precision impedance initial value.In processing impedance inversion,the choice of impedance initial value is very important, because different impedance values will be acquired when different impedance initial values are used, and this will affect the precision of lithologic interpretation precision. In this paper the author first advances the impedance scanning technique and proves it to be a method for acquiring higher precision impedance initial value by logs data and seismic data inversion result. The coincidance ratio of impedance initial value obtained by using impedance scanning to impedance initial value of the logs is about 99%.The impedance scanning technique provides a practical way and lays a foundation for high precision impedance and seismic lithologic inversion.