In this paper, the authors introduce the job selection strategy in the load balancing system——ILBOT (intelligent load balancer based on on-line tracing). In this strategy, the authors consider the influence upon response time of various kind of job caused by the various load environment. According to it, they estimate the benefit and overhead of transferring a job. They use a new selection strategy based on benefit and overhead in load balancing algorithm. The measurement results of the experiment show that it can improve mean response time of jobs and resource utilization of systems substantially.