A novel catalyst based on Fe1-xO (wustite) has been developed for ammonia synthesis. The technology has been without precedent. Its features are as follows : among all the iron catalysts for ammonia synthesis including Fe-Co catalyst, the catalyst has the highest activity, the easiest reduction and stronger mechanical strength. The cost is much lower than that of the catalyst containing cobalt. The industrial use of the catalyst indicated that it has remarkable effect of saving energy. The performance figures have reached the world leading level and the catalyst has been widely used in industry in China.