OBJECTIVE To evaluate clinical effects of expanded curettage and bone cement filling combined with internal fixation in treating Campanacci III giant cell tumor of knee joint. METHODS From January 2006 to December 2016, 21 patients with Campanacci III giant cell tumor of knee joint were treated by expanded curettage and bone cement filling combined with internal fixation, including 11 males and 10 females with an average age of(35.24±10.56) years old (ranged from 21 to 61 years old). The courses of disease ranged from 1.5 to 24.0 months with an average of(8.1±4.4) months. Among them, 8 patients were distal femur and 13 patients were proximal tibia. All patients were primary tumors. Musculoskeletal Tumor Society(MSTS) scores were used to evaluate lower limb function before and after operation. X-ray was used to observe healing of lesions and the occurrence of adverse reactions. RESULTS All incisions were healed at grade A without complications such as infection and internal fixation failure. All patients were followed up from 8 to 56 months with an average of (29.62±9.48) months. MSTS score at the latest follow-up 26.71±2.35 was higher than that of before operation 15.24±1.14, and had statistical significance(t=20.160, P=0.000). The results of X-ray at final following-up showed internal fixation was well, and no loosening and fracture of subchondral bone. Three patients recurred giant cell tumor and replaced with tumor prosthesis. CONCLUSIONS Expanded curettage and bone cement filling with internal fixation for the treatment of Campanacci III giant cell tumor of knee joint could effectively retain limb function and reduce tumor recurrence rate.