This paper used the three standard operational chlorophyll a concentration inversion algorithms OC2，OC3，and OC4 of SeaDAS software to carry out chlorophyll a concentration inversion in the Yellow Sea and East Sea of China and validate the results by using the measured chlorophyll a concentration data of the Yellow Sea and East Sea of China in 2003.The inversion results of OC3 and OC4 algorithms were obviously large，and the inversion results of OC2 algorithm were slightly large.In view of the shortcomings of these algorithms，this paper proposed a chlorophyll concentration inversion model based on ridge regression，and utilized the MODIS remote sensing data in 2003 to carry out chlorophyll a concentration inversion in the Yellow Sea and East Sea.After comparison with the measured data and F-test （F=25.893，p=0.000 ＜0.05），the mean absolute percentage error （MAPE）between model predictions and measured surface chlorophyll a concentrations was 21.8%，the root mean square error（RMSE）was 0.325mg/m3 and the coefficient of determination （R2）was 0.847，while the mean absolute percentage error （MAPE）between model predictions and measured surface chlorophyll a concentrations was 0.325 and the coefficient of determination（R2）was 0.847.The results showed that the inversion model can effectively overcome the deficiencies of OC2，OC3，and OC4 algorithms，with obvious advantages in accuracy and fitting degree.Therefore，the inversion model of chlorophyll a concentration based on ridge regression can effectively invert the chlorophyll a concentration in the offshore.