The okra fruit is easily lignified, whereas the fruit lignification would decrease the commercial value. In order to explore the aging mechanism of okra fruit, two cultivars, Z06 (easy to age), and Suyoukui 3 (not easy to age), were used for physiological indicators quantification and transcriptome sequencing at three developmental stages. The differences in fruit texture between cultivars or at different developmental stages was mainly caused by the accumulation of lignin, while cellulose and protopectin were also found with positive effects. The differentially expressed genes (DEGs) of the same cultivar at different fruit development stages were significantly enriched in the phenylpropane biosynthesis and secondary metabolite biosynthesis pathways. While the DEGs between the cultivars were found with enrichments in the phenylpropane biosynthesis pathway, the photosynthesis and photosynthesis antenna protein pathways. During the hardening stage of okra fruit, the gene PAL was found as key regulator that affected lignin accumulation. The SUS3 gene contributed predominantly to the accumulation of cellulose, and the down-regulated expression of the BGLU gene was also an important factor in promoting the accumulation of cellulose. Two genes GAUT6 and SUS6 largely contributed to the accumulation of protopectin, but most of the PME and PG genes had a negative contribution to the accumulation of protopectin. Lignin synthesis-related genes PAL6, PAL5, PAL1, CCR2, CYP84A1, CYP73A12, and photosynthetic pathway-related genes PSBP2 and CAB1R were important genes that affected the texture differences of two cultivars.