The invention provides a loading box applicable to axial and eccentric loading of an extended foundation. The loading box comprises a short column, a steel sleeve, a steel box, a stiffening plate, inner separating plates and mass blocks, wherein the short column and the foundation are cast in place together; the short column is designed as per load conditions identical with those of the foundation; the steel sleeve covers the short column and is connected with the short column under the effect of bolt pins; the stiffening plate and the steel box are connected with the steel sleeve by the aid of weld joints; a bottom plate of the steel box makes direct contact with the top of the short column; the inner separating plates are connected with the steel box by the aid of weld joints to divide the steel box into a plurality of cells; the mass blocks are directly placed in the cells; and different numbers of mass blocks are placed in the different cells, so that the loading process of the concrete foundation is realized. The loading box is applicable to outdoor tests for performing axial loading and eccentric loading on the concrete foundation, static loading is performed by the aid of the dead-weight of the mass blocks, and the loading box and the structure of the loading box are reliable in measurement, convenient to operate as a whole and high in controllability.