The invention discloses a test beam long-term loading system and method. The loading system comprises a lever, a tension bar, a distributive beam, a counterweight device, a hydraulic pressure weight adjusting device, a ground anchor and a force transmission and testing device; the design of a loading system is carried out using the lever principle, firstly based on the test requirements, the size of the applied load as required is set; after the determination of the size of the load, the length ratio of the short arm and the long arm of the lever is designed from the size of the test site, the size of the loading lever and other aspects, under the precondition that the weight of the lever is not taken into consideration; in theory, the larger is the length ratio of the short arm and the long arm of the lever, the larger is the weight applied to the force bearing point of the long arm, and the larger is the amplifying multiple of the load at the force bearing point of the lever, and the aim of applying relatively large load is further achieved by utilizing relatively small weight. The long-term loading system is easy to operate, the loading and unloading save time and labor, the performance is stable, and long-term testing is guaranteed. The long-term loading system in the later period does not require special maintenance, and basically is not affected by external conditions.