A four-year field experiment was carried out in six provinces and cities for studying the effect of clayey soil amelioration with coal ash produced by the wet method in power plants on crop yields. The results showed that by applying 15000 to 30000 kg/mu coal ash into soil, wheat yield increased by 12.7±5.8%,crop yield by 12.1±3.5%,and the rice yield by 13.5±7.0%,with a certain effect on the yields of foxtail millet, sweet potato, cotton, and vegetables Besides, after application of coalash, clay content of soil decreased, density and swelling value reduced, porosity of soil increased and the ratio of 3 phases (gas, liquid, solid) was adjusted. Coal ash could also improve the physical properties of clayey soil, increase soil P, and Si contents and promote microbial activities, thus raising soil temperature, enhancing the transformation of soil nutrients and creating a good soil environment for crop growth.