Lyocell was modified by low temperature plasma with different technics parameters,researching the surface characters and physical properties by SEM etc,using knowledge of chemical thermodynamics and dynamics,research and analyse in reaction mechanism,proves that its superiority to use this technics to modify or graft in Lyocell fiber surface.with the performance compare between unmodified or modified Lyocell fiber,the research reveal that modified by low temperature plasma,the Lyocell fiber reduced its fibrillation very obvious,but don't change its physical and mechanical properties.