Abstract: People have paid attention to the pollution of soil and water quality caused by using organic arsenic chemistry reagent to prevent and cure apple-tree canker in our apple area, so it has an important purpose to seek a harm-free way for sustaining development of apple. The tests studied the effect of prevention and cure on apple-tree canker with EM mud, EM liquid, 40%‘Fumeishen powder’ and contrast. The results showed that the EM mud was superior to the EM liquid, 40% ‘Fumeishen powder’ and contrast. The prevention and cure effects of EM in 2006 and 2007 were 92.7% and 93.5%, while the recurrence rates of canker scars 1.8% and 2.8% respectively. And the healing effect of scar is 50.4%. So, it was considered as a new way to prevent and cure apple-tree canker with EM mud.