A direct heat soil pasteurizer is suitable for soil mixture reusing process for Taiwan florist and nursery industries that are not equipped with steam boiler. A soil pasteurizer was designed and developed in cooperated with San-Shen Agricultural Machinery Co. Ltd. Field tests were carried out to evaluate the performance the machine. Soil was heated in the pasteurizer up to 85℃, and after a 60min. holding time the coldest spot was 75℃. The effect of pasteurization was evaluated by microbial total count and Rhizoctonia solani inoculation tests.