In the shallow water waveguide environment, time reversal (TR) processing based on the co-located receive and transmit array time-reversed the received signal and sent it back to the medium. The time reversal signal energy was focused on the target and reverberation was reduced. The signal-to-reverberation ratio was further improved by multipath compensation beamforming after the enhanced target echo signal was received. The beamforming output was correlated with a replica of the transmitted signal, the result of which was used to be test statistic for target detection. The time delay of signal arrival was used for target range estimation. In a lake experiment, the reverberation and focusing energy on target were compared between broad side (BS)and TR transmitting, and the result of which showed that time reversal processing had the ability of suppressing reverberation and enhancing the signal-to-reverberation ratio. In a lab waveguide, the advantage of time reversal processing was taken to detect a small bottom object. The lab waveguide experimental result showed that an active time reversal detection system not only can effectively detect a small bottom object but also measure the target range．