The spatial characteristics of stratification in Deukryang Bay were studied using observed data and analytical models. From the description of the density structure and its the potential energy anomaly (PEA) from observed data along longitudinal direction (from the mouth to head of the bay), we found that the stratification intensity could be changed strongly by density current effect during the spring-neap tidal cycle, and depth variation. To find out density current effect for the formation of the stratification in detail, we implemented a diagnostic approach by using the modified analytical model including density current, tidal current, surface heating and wind stirring. The model allowed for the observed similarities for the whole domain in the bay and increased tidal mixing efficiency value ε up to 0.006 - 0.007 as compared to the results without density current effect. We found that the density current effect was also an important key factor in determining the formation of the spatial distribution of stratification.