To explore the internal relationship between stalk qualitative trait and strength of the basal internodes in maize, this experiment selected different density-tolerant maize cultivars as materials. Random block design was used in the experiment to comparing the basal internode characteristics and analyzing the internal relation between lignin accumulation, enzymes activities and the rind penetration strength (RPS) under field conditions. The results showed that the dry weight per unit length (DWUL) and diameter of XY 335 was higher. The rapid formation period of stalk strength was different among different cultivars and was closely related to the lignin accumulation. The RPS formation period for density-tolerant cultivars was 5~7 days longer than XY41( a cultivar with poor density tolerance). The RPS and lignin accumulation amount were significantly higher than XY41 of 24.9%~36.6% and 12.5%~47.0%, respectively. Before the tasseling stage (VT) is the key period for the rapid accumulation of lignin. The activities of enzymes for lignin synthesis in the V12~V15 stage were significant or extremely significant correlated with the lignin accumulation in the tasseling stage (VT). Especially in V12 stages, the lignin synthesis-related enzymes of XY335 were significantly higher than XY41, the PAL, TAL, CAD and POD of XY335 were 1.85, 0.30, 0.11 and 0.42 U/mg higher than that of XY41. Which indicating that V12~V15 stage was crucial for the formation of maize basal internode stalk strength. The higher activities of enzymes in V12~V15 stage could effectively promoted the rapid accumulation of lignin, then improved the stalk strength, and thus enhanced the lodging resistance of maize stalk.