Esophageal squamous cell carcinoma (ESCC) is one of the most common and lethiferous cancers in the world. The function of miR-29a-3p has been reported in multiple human cancers as a key regulator of oncogenic processes. However, the function of miR-29a-3p in ESCC remains unclear. In this study, we found that enhanced expression of miR-29a-3p in ESCC cell lines not only suppressed cell proliferation, but also decreased the cellular motility including migration and invasion. Furthermore, luciferase reporter assay revealed insulin-like growth factor 1 (IGF-1) is the direct target gene of miR-29a-3p in ESCC cell lines. Experimental validation demonstrated that expression of IGF-1 was suppressed by miR-29a-3p on protein and mRNA levels. In addition, we detected the expression of miR-29a-3p and IGF-1 mRNA in 26 pairs early ESCC specimens which were at the stage of T1-2N0 and found that the expression of miR-29a-3p was significantly down-regulated in early ESCC specimens relative to adjacent normal specimens. Furthermore, we found a negative correlation between the expression of miR-29a-3p and IGF-1. This is the first time proving miR-29a-3p participates in suppressing onceogenic process in ESCC by targeting IGF-1. Taken together, these results suggested that miR-29a-3p was a tumor suppressor and might be a potential therapeutic candidate for the diagnosis and therapy of ESCC.