Rainbow table is the most commonly used tool in password cracking field. Rainbow table constructed by CPU occupies huge memory space and time, which is the biggest problem in rainbow table application. This paper concentrates on the research of the bottleneck problems of rainbow table: search time, construction time and memory space. By building a model of rainbow table parameters and time-space to analyze parameter values that can be used in application, high speed GPU was adopted to optimize construction method of rainbow table. A rainbow table password attacking system based on distributed GPU was designed and realized, including cipher extraction module, cipher distribution module, GPU managing module and rainbow table module. Test results in actual password attacking system show that the method can effectively develop password cracking efficiency, reduce rainbow table utilization of space and time and increase actual password length that rainbow table can attack.