Based on analysis of linear relationship between aerosol parameters and cloud parameters in MODIS data,indirect aerosol effect was discussed over the China offshore region.The result showed that indirect aerosol effect indeed exists over the China offshore region.Meanwhile,indirect aerosol effect varies with time,which is a result of the changing of aerosol variety and water vapor content during different seasons.During the summer(e.g.August) time,anthropogenic aerosol is the most important component of aerosol in cloud,which is an effective cloud condensation nuclei.The dominance of anthropogenic aerosol,coupled with sufficient water vapor,contributes to the remarkable indirect aerosol effect in summer.The analysis results show that strong positive correlation exists between aerosol optical thickness(AOT) at 550nm and number of cloud condensation nuclei (CCN),negative correlation exists between AOT and cloud effective radius (CER),and positive correlation exists between AOT and cloud optical thickness(COT).While during the spring(e.g.April) time,dust is the dominant component of aerosol,which is a bad cloud condensation nuclei,and the water vapor content decreases.As a result,both the positive correlation between AOT and CCN,and the negative correlation between AOT and COT,turn to be weak.While the correlation between AOT and CER changes from negative in summer to weakly positive in spring.The indirect aerosol effect is not pronounced in spring over china offshore region.