The changes of amino acid and other related indexes in chicken soups which were concentrated under atmospheric pressure and vacuum were studied. The results were as follows: with the increase of concentration ratio, the contents of crude protein, oligopeptide and reducing sugar in chicken soups were gradually reduced. Under the same concentration ratio, the crude protein content in atmospheric concentration chicken soups was higher than that in vacuum concentration chicken soups (P＜0.05), while the oligopeptide content in vacuum concentration chicken soups and the reducing sugar in chicken soups with concentration ratio greater than 1∶2 were higher than that in atmospheric concentration chicken soups (P＜0.05). The content of total free amino acids in chicken soups, both concentrated under atmospheric pressure and vacuum, increased first and then decreased with the increase of the concentration ratio (P＜0.05). When the concentration ratio up to 1∶2 under atmospheric pressure and 1∶3 under vacuo, the content of the free amino acids was highest. With regard to the same concentration ratio, the content of total free amino acids in atmospheric concentration chicken soup was significantly higher than that in vacuum concentration one (P＜0.05). Therefore, the conditions and proportion of evaporation and concentration had a great impact on the change of free amino acids in chicken soup, which in turn affected its flavor quality.