This brief describes various methods of chitosan nano-materials synthesis, with detailed discussion of various factors effecting its synthesis process, stability and physicochemical properties. Chitosan is naturally occurring biopolymer derived from chitin. Due to the unique biological properties of chitosan nano-materials such as antimicrobial, plant growth inducer, plant defense modulator, chitosan has gained attention in fields of plant sciences. Book further extended the details of different types of chitosan nano-materials specially for plant applications along with its future prospects in plant protection and growth. Bioactivities of chitosan nano-materials and its mechanism have also been covered. This book aims to widening the understanding of the synthesis, characterization and use of chitosan based nano-materials in plant system. .