Soil culture and pot experiments of bio-ash mixed with soil were employed to investigate the effects of bio-ash on soil properties and the seedling growth of rape.The results showed that the contents of soil effective nutrients increased with the increase of bio-ash application amount.Particularly the contents of available P and K in soil increased significantly.With the increase of ash amount,pH of soil increases and tends to neutral.The average increase is 7.78%.In low level of fertilizer,the increase of ash application amount is more conducive to the improvement of the soil available P,and the maximum increase is up to 4.2 times.The effect of changes in fertilizer application amount on the P absorption of rape is little.But with the increase of ash application amount,the content of total P in rape emerges the trend of increase first and then decrease.In middle level of fertilizer,the ash enhances the capacity of K absorption of rape plants,and the maximum increase of the content of total K in rape is up to 44.43%.In high level of fertilizer,the ash does not affect the capacity of K absorption of rape plants.The manifestation of antagonism between K and Ca,Mg in rape can be changed by the ash application.With the increase of ash application amount,the content of Ca and Mg absorption of rape emerges the trend of increase first and then decrease.All in all,a reasonable proportion of integrated fertilization with bio-ash and chemical fertilizers can promote the migration and transformation of nutrient elements in soil-plant system and the seedlings growth of rape.