Abstract: Abstract： Objective To compare the sealability of the three root canal pastes: Vitapex paste、AH-Plus paste and GuttaFlow. Methods Thrity single rooted human teeth were chosen and randomly divided into three groups with 10 teeth in each group. Group A was filled with Vitapexas paste. Group B was filled with AH-Plus paste. Group C was filled with GuttaFlow. Section was done to each tooth 2,4,6,8 mm from root apexes. MIAS-2000 images were used to analyze and calculate the cross-sectional area of canal (AC) and perceentage of voild-filled area (PV). Record the results and make statistical analysis. Results The values of AC in three groups were different at the distance of 2,4,6,8 mm from root apexes but without statistical significance(P>0.05). PV value of group C was statistically different with those of the other groups 2,4,6,8 mm from root apexes (P<0.05). PV values of group A and B had statistical significance 2,4mm from root apexes (P<0.05), but those of group B and C had no statistical significance(P>0.05). PV value in each group 6,8 mm from root apexes had statistical significance (P<0.05). Conclusions GuttaFlow sealer and the AH-Plus sealer show higher density of root canal filling in various parts of the root canals; Vitapex sealer shows lower density of root canal filling.