The Paper will discuss influence of liquid chlorine and chlorine dioxide and mixture of both on livingness of Maize root population. The result of experiment show that liquid chlorine in great does poisoned root, and reduced obviously activity of roots. Other disinfectors have no effect on activity of roots, but affect livingness of Maize Root-population. And the right dose of liquid chlorine is 8mg/l，the right dose of chlorine dioxide is 6mg/l, the right dose of mixture is （4＋2）mg/l.