The great concern of managers, owners, and water users from irrigation reservoirs is to ensure the safety of the dam in particular and hydraulic work in general. The important safety assessment criteria for seepage analysis of embankment dam are determination the position of the phreatic line, checking the seepage gradient, and inspection the seepage pressure in the dam foundation. This article focused on evaluating the seepage safety of Vinh Son B dam by establishing a standard-data-set and checking whether the observed values of the project indicate a safe level for the dam or not. Quantifying the seepage safety level is based on the physical properties of the embankment and foundation soils, the water level in the reservoir, and other factors, which is an important content in the dam safety inspection. The method of establishing a standard-data-set for seepage analysis in this study has shown that the seepage circumstance of the dam was currently at a safe level.