Carrier aggregation technology is one of the key technologies in LTE-A system

which can effectively solve the bandwidth extension problem in LTE-A system. Carrier aggregation select proper the component carrier during transmission will make the data with high reliability. This paper presents a component carrier selection algorithm to improve the reliability of data transmission

considering both component carrier channels quality and load balancing

then select the component carrier. The simulation results show that this algorithm can effi ciently aggregate the component carrier and decrease bit error rate and block error rate of data transmission

reducing the average number of transmission

thereby increasing the reliability of data transmission

reducing system overhead.