Abstract: To extend microwave heating applications, researches of microwave deicing have been done. The rectangular horn antennas were designed to match the load of asphalt admixtures, to improve the heated areas and decline unheated areas effectively. Horns autennas with different slopes are designed for numerical analysis and experiment. In the experiments, the input voltage standing wave ratio of these antennas were measured and the contrasts of effects were made after the asphalts mixtures were heated for the same time. The data was analyzed for better use of these horns, and finally the horn antenna with slop angle of 15 degree was detected to fit the request of near asphalt mixtures heating well in deicing．