Objective To compare the difference and rationalities between Harmm and Zhou' s formulae for expected acid-base compensation in acid-base imbalance. Methods 745 cases of arterial blood gas analysis results of acid-base disorder were evaluated respectively by Hamm and Zhou' s formulae, and the concordance was judged. Results For metabolic acidosis ( 108 cases), the concordance rate was 70. 4% between Hamm and Zhou's( Kappa value =0. 41 ,P ＜0. 01 ) ;for metabolic alkalosis ( 132 cases) ,the concordance rate was 59. 1% ( Kappa value =0. 18 ,P ＜0. 05) ;for acute respiratory acidosis(81 cases) ,the concordance rate was 65.43% ( Kappa value = 0. 31, P ＜ 0. 01 ) ;for acute respiratory alkalosis ( 168 cases), the concordance rate was 54. 8% ( Kappa value = 0. 24%, P ＜ 0. 01 ); for chronic respiratory acidosis ( 119 cases ), the concordance rate was 67.2% ( Kappa value = 0. 41, P ＜ 0. 01 ) ;for chronic respiratory alkalosis( 137 cases), the concordance rate was 66. 6% ( Kappa value = 0. 43, P ＜ 0. 01 ). Conclusion The difference between Hamm and Zhou' s formulae for expected acid-base compensation in acid-base imbalance was obvious. The Zhou' s expected max compensation coefficient were slightly higher than the primary adopted compensation coefficient.