• Have fully understood the study and voluntarily signed the informed consent;

• Age from 2 to 70 years old (inclusive), both male and female;

• histologically or cytologically confirmed diagnosis of primary bone tumor

• having at least one measurable lesion (RECIST 1.1);

• The patient has not been treated before (including any chemotherapy, targeting, immune and other drugs);

• The functions of major organs and bone marrow are basically normal;

• ECOG performance status 0 or 1 (PS 0-2 points for amputees);

• Expected survival ≥12 weeks;

• Blood test (without blood transfusion within 14 days) 1) Neutrophil absolute value ≥1.5×109/L, platelets ≥100×109/L, hemoglobin concentration ≥9g/dL); 2) Liver function test (aspartate aminotransferase and glutamic aminotransferase ≤2.5×ULN, total bilirubin ≤1.5×ULN; In case of liver metastasis, AST and ALT≤5×ULN); 3) Renal function (serum creatinine ≤1.5×ULN, creatinine clearance (CCr)≥60ml/min);

⁃ Fertile male or female patients voluntarily used effective contraceptive methods, such as double barrier methods, condoms, oral or injectable contraceptives, intrauterine devices, etc., during the study period and within 6 months of the last study dose. All female patients will be considered fertile unless the female patient has undergone natural menopause, artificial menopause or sterilization (such as hysterectomy, bilateral adnexectomy or radiation of the ovary).