For that channel features extracted by the two communication parties are significantly different， resulting in a low key generation rate and consistency in wireless communications， a Key Generation algorithm based on cyclic Grouping of difference Thresholds （TGKG） was proposed. First， the Channel State Information （CSI） was grouped with a threshold， by which the interval of data within the group was greater than the threshold， so that quantization error and hence key disagreement rate was reduced. To avoid inconsistent grouping due to data errors， circular grouping was performed on one side only. Meanwhile， the algorithm was applied to quantize real part and imaginary part of CSI， respectively， significantly increasing key generation rate. The advantages of the proposed algorithm was proved in terms of key disagreement rate， key generation rate and security by probabilistic and information theoretic formulas. The experimental results show that the key disagreement rate of the proposed algorithm for both communicating parties is about 2%， and the key generation rate is about 142% under the Signal-to-Noise Ratio （SNR） condition of 5 dB.