Accurately determining circulating pressure loss during drilling is very important for reducing downhole accidents, improving safety drilling efficiency. Because of large error in circulating pressure loss from conventional calculation, it is necessary to make improvement. By power-law drilling fluid simulation, Reynolds equation is deduced from pipe and annulus power-law fluid, so as to arrive at the laminar flow of air circulating loop of pressure loss calculation model. It is proven that the model in determining the deep circulation pressure consuming calculation is simple, with high accuracy, low error and provides a new method for accurately calculate the circulating pressure loss during deep drilling operations.