The invention discloses a DDOS attack traffic cleaning method and system. The method comprises the steps that communication connection is built for detection equipment, cleaning equipment and a router; the detection equipment gives a cleaning instruction for an attacked target to the cleaning equipment; the cleaning equipment sends a traffic lead request for the attacked target to the router; the router leads the traffic of the attacked target to the cleaning equipment, and the cleaning equipment cleans the traffic; after attack is finished, the cleaning equipment keeps traffic lead for the attacked target till lead keeping time is up. The system comprises a communication building unit, an initialization unit, an attack detection unit, a lead request unit, a cleaning unit and a lead keeping unit. Due to the fact that lead is kept after cleaning of the attack traffic is finished, an attacker is effectively prevented from avoiding cleaning intervals of the traffic cleaning system by using a pulse type attack method, and therefore a better cleaning effect is achieved. The DDOS attack traffic cleaning method and system can be widely applied in the field of attack cleaning.