An apparatus for testing tangential and normal resistance of an anchor chain and soil under an equivalent elastic boundary and a method therefor, and the apparatus includes a support frame, a transmission device (4), an air pressure loading system, a test box (5), a vertical displacement applying part (6), a tangential anchor chain unit (7), a normal anchor chain unit (8), etc. The present disclosure can, by using a spring of equal stiffness to simulate the elastic boundary and being capable of overcoming an influence of boundary conditions, greatly reduce a size of the test box, thereby effectively saving materials and reducing difficulty of a test operation; moreover, it integrates the normal and tangential resistance tests into one, which can measure tangential and normal interactions of the anchor chain and the soil at the same time.