To　popularize　the　application　of　air-entraining　agent　(AEA)　in　road　cement　concrete　of　China,　five　types　AEAs　were　selected　to　research　the　effects　of　AEA　on　compressive　strength　and　air　void　characteristics　of　hardened　concrete.　The　results　showed　that　suitable　air　contents　couldn＇t　reduce　the　compressive　strength　of　hardened　concrete　excessively,　which　made　the　concrete＇s　spacing　factor　reduce　obviously　and　significantly　improve　the　frost　resistance　of　concrete.　The　types　of　AEAs　would　make　significant　effect　on　the　relevance　between　the　air　contents　of　freshly　mixed　concrete　and　hardened　concrete.　There　were　substantial　differences　in　spacing　factor　among　concretes　that　used　different　AEAs　even　through　the　mixed　concrete　which　had　the　same　air　contents.　The　method　to　determine　the　frost　resistance　of　hardened　concrete　only　through　the　air　content　of　fresh　concrete　maybe　had　a　great　deviation.