The balance in cooling water systems is the main factor which in fluences the effect of water treatment chemicals,but the destruction of the b alance make it more difficult to treat,demanding more in the performance of wat ertreat chemicals and the leval of on-the-spot services.Thus the contradictio n between the balance and de-struction promote the development of water treatm ent technology,and provide good bases in wastewater reuse te-chnology.