Abstract: On the basis of a high correlation coefficient of the relationship between dry bulk density and porosity of soil, the empirical formula of porosity of soil has been established. It's application to the fields of agriculture and soil science for more than ten years it has a practical value in production and research, and it is a convenient formula with high accuracy, economy and easy to apply. At the present it has been found wide use.In the process of discussion of this paper, we attempt to draw attention of scientists and engineers in the fields of geotechnical engineering,soil mechanics and soil technology, it is sincerely hoped that they can make research on this formula.