MicroRNAs (miRNAs) are involved in the pathogenesis of intrahepatic cholangiocarcinoma (ICC). However, the role of microRNA‑31 (miR‑31) in ICC has yet to be elucidated. In this study, we demonstrated that the expression of miR‑31 was significantly upregulated in ICC tissues and the human ICC cell line HCCC‑9810, when compared with that in normal adjacent tissues. Bioinformatic analysis and a dual‑luciferase reporter assay revealed RAS p21 GTPase activating protein 1 (RASA1) to be a direct target of miR‑31 in HCCC‑9810 cells. Further investigation showed that the protein expression level of RASA1 was significantly decreased in ICC tissues, suggesting an inverse correlation between miR‑31 and RASA1 expression during the tumorigenesis of ICC. Moreover, the forced downregulation of miR‑31 by its inhibitor in HCCC‑9810 cells significantly inhibited cell proliferation and promoted cell apoptosis. However, when the cells were cotransfected with miR‑31 inhibitor and RASA1‑specific small interfering RNA (siRNA), these changes were attenuated. Further analysis of the molecular mechanism showed that the activity of the RAS‑mitogen-activated protein kinase (MAPK) signaling pathway was significantly decreased in miR‑31‑downregulated HCCC‑8910 cells, while cotransfection with miR‑31 inhibitor and RASA1‑specific siRNA attenuated this effect. These results indicate that the downregulation of RASA1 by miR‑31 promoted cellular proliferation and inhibited cellular apoptosis, partially by upregulating the activity of the RAS‑MAPK signaling pathway in ICC. In conclusion, the present study revealed important regulatory functions of miR‑31 and RASA1 in ICC, indicating that miR‑31 and RASA1 may become promising diagnostic and/or therapeutic targets for ICC.