According to the characteristic of underwater high speed moving target, a signal detection and parameter estimation fast algorithm based on wideband Pro and Con frequency modulation HFM signal was advanced and a simulation on the algorithm was carried on. Through the lake test which simulates the echo of underwater high speed moving target, a DSP system with a core of TMS320C6701 was designed, realizing the fast algorithm of echo processing under the low SNR. The result of lake test indicates that the fast algorithm based on wideband correlative processing and its DSP system can effectively accomplish the detection and parameter estimation on the echo of high speed moving target under low SNR.