The invention provides testing equipment for normal temperature and high temperature stress relaxation of a flat spring. The testing equipment mainly comprises a base, limiters, an upper plate, a pressure sensor, a pressure head, a front lateral plate and a rear lateral plate, wherein the front lateral plate and the rear lateral plate are respectively fixed on the front and the rear sides of the base, the pressure head is fixed at the lower end of the pressure sensor, the upper end of the pressure sensor is fixed on the upper plate, the upper plate is positioned right above the base, the upper plate and the base are fixed together through two limiters, one end of a flat spring to be tested is fixed on the upper side of the front lateral plate through a bolt, the other end of the flat spring extends into a groove formed in the upper side of the rear lateral plate, bottom surfaces of the grooves in the upper lateral surface and the rear lateral surface of the front lateral plate are positioned on the same horizontal plane, and the pressure head is in line contact with the sample. The equipment provided by the invention is simple and convenient to design, is easy to process, requires no determination of the relationship between the stress and the deflexion, is simple to measure and obtain the testing data, ensures the accuracy, the repeatability and the reproducibility of the stress testing results, and improves the accuracy of the measured data.