Abstract: Microwave over-the-horizon radar can detect long distance and low altitude targets by means of the evaporation ducts over sea, however, the super refraction and multi-path propagation effects produce radar blind areas in evaporation duct where targets can not be detected. A method of antenna height optimization based on object function for microwave over-the-horizon radar is proposed in this paper. Radar detection performances are simulated in the three evaporation duct situations of stable stratification, neutral stratification and unstable stratification using numeric algorithm of radiowave propagation and radar performance evaluating models. The results of optimized antenna height is obtained for specific evaporation height and area weight functions. The method proposed can be used as a reference in microwave over-the-horizon radar design, detection performance analysis and self adaptive technology development in atmosphere environment.