HTCondor, a batch system characterized by its matchmaking mechanism, schedules job in FCFS way, so its performance is not ideal as expected. Backfilling is a technique to address the above problem. Most backfilling algorithms are based on CPU information and have large room for improvements with considering other resource information. The K-resource aware scheduling algorithm Backfill Balanced (BB) selects backfill job which can best balance the usage of all resources and achieve better performance compared with the classical backfilling algorithm. However, BB does not realize that small jobs’ impacts on resource utilization are negligible and they mainly contribute to reduce the average response time. Here we propose the IBB algorithm, which utilizes the characteristics of small jobs to guide a better job selection. We implemented IBB on HTCondor to improve its performance. Experiments results show that IBB can provide up to 60 % performance gains in most performance metrics compared with BB.