A ternary-mobile phase program with acetonitrile, water and tetrahydrofuran was developed to identify and quantify 22 carbonyl compounds species by HPLC-UV. The analytical method succeeded in separating acrolein from acetone. Two sampling sites (industrial district and business district) were chosen to study carbonyl compounds levels in ambient air of Shanghai. The results indicated that formaldehyde, acetaldehyde, acetone and 2-butanone (C1-C4 carbonyl compounds) were the most abundant carbonyl compounds in ambient air of Shanghai. The four carbonyls together accounted for 78.95% (industrial district) and 77.63% (business district) of the total carbonyl compounds, respectively. In industrial district, the mean concentrations of formaldehyde, acetaldehyde, acetone and 2-butanone were 10.36, 15.32, 9.95 and 4.56 microg/m3, respectively; in business district, their mean levels were 10.00, 10.04, 7.80 and 2.81 microg/m3, respectively. So the mean levels of C1-C4 carbonyl compounds in industrial district were higher than in business district. The higher concentrations of the total carbonyls were also found in industrial district (53.64 microg/m3) than in business district (41.96 microg/m3). A similar diel variation occurred to the two districts that higher carbonyl concentrations were shown in morning peak and nighttime than in other three periods.