Physical layer security techniques utilize the wireless channel environment to dynamically generate keys,however,in quasi-static environment,slow channel transformation leads to insufficient key randomness and security.Here,a Backtracking Scrambled Key Generation (BSKG) algorithm is proposed.First,the real and imaginary parts of the channel coefficients are split and quantized to generate a longer key,which is reconciled,then the sum of the inconsistent indexes between the current key and previous key is used to generate a scrambling code to scramble the current key.Simulation shows that,compared with the existing multi-dimensional information and artificial randomness key generation method,the proposed algorithm has higher key generation rate and security,and the key leakage rate is close to 0.5 with the increase of the one-time pad key generation times,even if more relevant channel coefficients have been eavesdropped.The upper bounds on the probability of successful eavesdropping and their variations with the number of key generation N for general and bad channel conditions are estimated using semantic security and information-theoretic inequalities,respectively,when giving certain parameters,the upper bounds for these two cases turn out to be 2^-77N and 2^-23N.