In long term evolution (LTE) uplink random access, preamble detection is an important step. Because preamble sequence is long, the traditional receiver algorithms have a larger computation burden. Downsampling was introduced to reduce the computation burden. Several improvements were made to the traditional receiver algorithms. The computation burden of receiver algorithm after improvement decreases greatly in comparison with the algorithm before improvement. Take format 0 for example, the computation burden of algorithm before improvement is 120 times as much as the algorithm after improvement in an operation cycle. Simulation results show that the detection performance of algorithm after and before improvement almost don’t make any difference. The algorithm after improvement shows good performance in various wireless channels.