Provided is a suspension-bridge main cable experimental device, comprising a main cable (1) for an experiment, a temperature-humidity sensor (2), a pressure sensor (3) and a hollow metal pipe, the external diameter of which is slightly greater than that of the main cable for the experiment. The main cable for the experiment is wrapped by the hollow metal tube to replace a main cable on an actual testing point. The metal tube (1) is provided with a small notch as a point for testing the temperature and the humidity of the main cable for the experiment. The temperature-humidity sensor is disposed inside the metal tube and at the notch. A signal line of the temperature-humidity sensor is let out from the interior of the metal tube. The pressure sensor is connected with a port of the metal tube at the external of the main cable for the experiment. The technical scheme of the utility model is easy to realize.