The magnetic hysteresis loop is a significant performance of ferromagnetic material.The different-size specimens were fabricated and studied on the basis of magnetomechanical coupling tests.The curve of relationship between model size and magnetization intensity is obtained and hysteretic curve is described in the different conditions.The results indicate that the influencing law is reflected based on size effect of model specimens and performance of magnetic hysteresis and magnetization intensity.The results indicate that the size of Q235 steel model specimens is considerably influential in the magnetic hysteresis loop and magnetization, which accounts for an evident size effect.