Based on response surface analysis, influences of microwave treatment temperature, treatment time and input power on decreasing ratio of formaldehyde(DRF) from medium density fibre board(MDF) were studied. The results show that increasing treatment temperature, increasing treatment time at high temperature, or increasing input power at low temperature will increase the DRF of MDF specimens. However, at high treatment temperature, the increase of input power will reduce the microwave treatment effect. The optimum treatment effect is obtained at treatment temperature of 60℃, treatment time of 40min, and input power of 317W. Under this optimum condition, the DRF of MDF specimen is 59.31% and its main mechanical properties decrease slightly.