Objective To measure the expression levels of CGRP, Syn, GFAP, Caspase 3, and IL?1β after indole?3?propionic acid treatment of rats with spinal cord injury, and investigate the effect and mechanism of indole?3?propionic acid in motor and sensory functions in rats. Methods A total of 105 SD rats were randomly divided into three groups: sham operation, normal saline, and indole?3?propionic acid. The spinal cord injury model was established by striking the spinal cord with heavy objects, and then indole?3?propionic acid was injected into the abdomen. On days 1 and 3 day, and weeks 1 ~ 4, an incline plate test, BBB score, and tail dump test were performed to evaluate changes in motorand sensory functions of rats. Expression of CGRP, Syn, GFAP, Caspase 3, and IL?1β in the spinal cord of rats at each time point was detected by immunofluorescence and Western Blot. Coexpression of CGRP with GAP43 and Necab2 was observed by double immunofluorescence. Results (1)The inclined plate test and BBB scores of the indole?3?propionic acid group were significantly higher than those of the normal saline group (P< 0.05). The latency of the tail flick test in the indole?3?propionic acid group was significantly higher than that in the normal saline group from day 3 after the operation, and returned to almost normal at week 3 after the operation (P< 0.05). (2) CGRP and Syn?positive cells reached a peak in normal saline and indole?3?propionic acid groups at week 2 after the operation, and significantly more cells were observed in the indole?3?propionic acid group than in the normal saline group (P< 0.05). GFAP?positive cells in saline and indole?3?propionic acid groups reached a peak at week 2 after the operation and then decreased, but the number of cells in the indole?3?propionic acid group was significantly lower than that in the normal saline group (P<0?? 05). Caspase 3?positive cells in indole?3?propionic acid and normal saline groups decreased gradually after the operation, and the number of caspase 3?positive cells in the indole?3?propionic acid group was significantly lower than that in the normal saline group (P< 0.05). (3)At week 2 after the operation, CGRP and GAP43 were obviously coexpressed, and CGRP and Necab2 were complementary in adjacent cells. (4)At week 2 after the operation, CGRP and Syn expression in the indole?3?propionic acid group was significantly higher than that in the normal saline group, while GFAP, Caspase 3, and IL?1β protein expression was significantly lower than that in the normal saline group (P< 0.05). Conclusions A high dose of indole?3?propionic acid after spinal cord injury significantly enhanced the expression levels of CGRP and Syn, and CGRP was complementary to Necab2 and coexpressed with GAP43, which is beneficial to the calcium ion balance, regeneration, and synaptic remodeling. By inhibiting expression of GFAP, Caspase 3, and IL?1β in the spinal cord, the tissue inflammatory response to injury was reduced, astrocyte activity was inhibited, and apoptosis in the spinal cord was reduced, which was beneficial to the survival of nerve cells in the injured area, preventing the formation of glial scars in spinal cord tissue, restoring the sensory and motor functions of limbs, and rebuilding the morphological structure of spinal cord tissue.