Abstract: The characteristics of several kinds of powders of medium temperature abradable seal coatings were analysed.The different hardness of the coatings were prepared for one kind of powder by changing spray parameters.The microstructhe and phase were analyed. The effects of the characteristics of the powder and the spray parameters on the microstructure and the basic properties of the coatings were probled. The results show that the particles of 307 (Ni/graphite) domestic powder is coarse, is not well wraped, the microstructure microstructure of the coating made by the powder is lossen, the hardness of the coating is low. because 310(AlSi-graphite) domestic power is fine, the hardness of the coating prepared by the powder is higher than that required by Metco. Acorrding to the hardness of the coatings, the 313(AlSi-graphite) and 601(AlSi/polyester) domestic powder is good. The hardness of 307, 310 coatings is adjusted easy by changing flame spray parameters, but the hardness of 313, 601 coatings is not easy adjusted by changing plasma spray parasmeters. The oxide occurs in the flame sprayed coatings, but the oxide in the plasma sprayed coatings is not examined. The bonding strength between the coating and the substrate can be not evaluated by pull-off method.