Abstract: An on-ground MWD(measure while drilling) decoding system was designed based on the situation that many foreign devices have been used for the MWD in most oil fields in China.In this system,the explosion-proof tank and the on-ground collection box were integrated together as the data collection unit.First,FIR(finite impulse response) digital filtering was applied in the on-ground decoding algorithm to de-noise the mud pulse signal,of which the pump pulse base-value was then decreased by using relevant algorithm that could adjust the base-value.Next,the waveform of the mud pulse signal which has been treated by Manchester encoding within three bit cycles was analyzed;and the fuzzy clustering algorithm was also adopted for the recognition of the mud pulse signal.Experimental results show that this device can correctly extract and recognize the mud pulse signal;meanwhile the decoding process is simple and useful,with high reliability and low error rate,making it applicable to engineering projects.