This is a single-arm prospective phase II clinical trial to investigate the efficacy and safety of adjuvant concurrent chemoradiotherapy with simultaneous integrated boost following hepatectomy for intrahepatic cholangiocarcinoma with narrow margin (\<1cm) or nodal involvement. Eligibility patients will receive IMRT or VMAT. The prescription dose to high-risk area of tumor bed or positive lymph node was planned at 55-60Gy and the prescription dose to lymphatic drainage regions was planned at 40-45Gy in 20-25 fractions. During radiotherapy, patients will concurrently receive capecitabine (1600 mg/m² on days 1-14, every 21 days for 2 cycles). After radiotherapy, maintenance therapy with capecitabine will continue (2000 mg/m² on days 1-14, every 21 days for 6 cycles). For patients who cannot tolerate capecitabine, S-1 will be used as an alternative. The primary endpoint is 2-year recurrence-free survival. The secondary endpoints are 2-year overall survival, local-regional control rate and incidence of grade 3 or higher adverse events.