Abstract: This invention is a method for determining the compressive strength of cores obtained from concrete or similar materials by applying the load on 4 lines on the core cylindrical surface through a specially designed but very simple apparatus. The four loading lines are uniformly distributed on the circumstance of the test section of the core through using the apparatus so that the core is compressed in two diametrical directions—dual-dual directions orthogonal to each other. The stresses in the test section of cores are in three dimensional compression state and thus the test is of compressive nature. This invention avoids the trimming, capping, and curing operations which the conventional core test has to follow. Moreover, some factors that may result in the reduction in the reliability and the practical benefit of the core test can be greatly restrained or removed.