Abstract: To investigate the relationship among rice yield loss, the golden apple snail (GAS) (Pomacea canaliculata Lamarck) density and damage beginning time, the GAS was added to early rice field, late hybrid rice field and single late rice field artificially from 2007 to 2009. The results showed that, the earlier GAS was added to field, the more damage GAS caused. It was also identified that the more GAS added to the field, the more damage GAS caused. The power function equations could be used to describe the relationship between GAS density and yield loss. There should be less than 1 per m2 in early rice and field or 3.5 per m2 in late rice field if the yield loss was expected blow 5%. In early rice field, lower density was beneficial for higher survival rate. Although the survival rate was low in late rice field, the oviposition capacity would be higher with low density. It was important to control GAS after rice transplant. And preventing GAS before rice transplant would be better. To reduce yield loss, rice seedling should be added in time if seedlingless ridges happened.