By using the error detecting character istics of parity check matrix codes and the high correcting capability of cascade error correction algorithm,a high-eff iciency cascade error correction protocol is proposed.The optimum parameters of the protocol are obtained through theoretical analysis.The error cor rection efficiency and the capability of a single round error correcting are experimentally studied by usin g simulation data.Finally,the optimal parameter selection scheme with different initial bit error rates is obt ained.Multi-round error correction experiments are carried out to investigate the final key generation efficiency under different initial error rates.The cascade error correction experimental results show that when the initial bit error rates are 3%,6% and 10%,the corresponding final key generation efficiencies are 77.67%,63.21% and 46.82%,respectively. Experimental and theoretical results comparison shows that the final key generat ion efficiency of the proposed protocol is close to the upper bound of the theor etical value.