As a kind of cheap， easily accessible and environmentally-freindly absorbent， non-food biomass is very effective in treating the ammonia -nitrogen in wastewater. This paper briefly introduced the processing method of ammonia nitrogen in wastewater treatment， focusing on the current situation of treating ammonia-ni- trogen by non-food biomass. Then， different kinds of non-food biomass were modified in various ways for am- monia-nitrogen adsorption， and the mechanism of adsorption was expounded accordingly. Based on the existing research findings， the key points and prospects of its future were presented.