In conclusion, we found that circSLCO1B3 was correlated with poor prognosis in ICC and could promote the proliferation, migration and invasion via the miR-502-5p/HOXC8/SMAD3 axis, more than that, it facilitated immune evasion via antagonizing PD-L1 degradation in ICC. The gene discussed is SMAD3; the disease is intrahepatic cholangiocarcinoma.