Based on the analysis of 69 specimens of Boleophthalmus pectinirostris (Linnaeus, 1758) collected from the coastal estuaries of Thanh Hoa Province, this study examines the correlations between morphological characteristics of different body parts and the standard length and head length of this species. First-order linear regression analysis was used to assess these relationships through the correlation coefficient R. The results indicate that the morphological measurements are positively correlated with standard length and head length. Specifically, measurements associated with head length, the second dorsal fin, the pelvic fins, and the anal fin show strong correlations with standard length, with R > 0.7 (HL, PreA, PreA1, PreP2, LD2, LA, BD.P2, BD.A, D.P2-A, and BD.D2) and R > 0.8 (PreD2). The minimum head width is strongly correlated with head length (R = 0.7). These findings indicate that morphological characteristics associated with the positions of the second dorsal fin, anal fin, and pelvic fins are important for the morphological analysis of Boleophthalmus pectinirostris.