The calculation of the real contact area between rough surfaces is an important prerequisite for studying the contact characteristics of mechanical joints. However, it is challenging to accurately calculate the real contact area between rough surfaces by existing theoretical and experimental methods. Therefore, an efficient and practical equivalent calculation method for the real contact area between three-dimensional(3D) rough surfaces based on two-dimensional(2D) profiles is presented in this paper. The main advantage of the presented method as compared with those available in the literature is that the real contact area can be predicted only by the section of the 3D rough surfaces in contact, which greatly reduces the computational cost. The sampling strategy of sections is studied to improve the accuracy of the proposed method. The accuracy of the proposed equivalent calculation method is verified by numerical simulation. The results show that the proposed equivalent calculation method can efficiently predict the real contact area between rough surfaces within the scope of engineering application.