Inclusion Criteria:  1. Subjects fully understand and voluntarily participate in this study and sign informed consent; 2. Age ≥18 years, without gender limitation; 3. Histologically confirmed diagnosis of bone or soft tissue sarcoma; 4. Metastatic or unresectable bone or soft tissue sarcoma that has failed at least one prior line of therapy; 5. At least one measurable lesion according to RECIST v1.1; 6. Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1; 7. Adequate organ function defined as:  Absolute neutrophil count (ANC) ≥1.5 x109/L (No G-CSF treatment within 1 week prior to the laboratory test); Hemoglobin ≥ 110 g/L (No red blood cell transfusion within 1 week prior to the laboratory test); Platelet count ≥ 100 x 109/L (No platelet transfusion within 1 week prior to the laboratory test); Creatinine ≤1.5 x upper limit of normal (ULN); Total bilirubin ≤1.5 x ULN (≤3.0 x ULN for liver metastasis); Aspartate aminotransferase (AST) and/or alanine aminotransferase (ALT) ≤ 3 x ULN (≤5.0 x ULN for liver metastasis); Coagulation: Prothrombin time (PT) or International Normalization Ratio (INR) ≤1.5 x ULN (≤3.0 x for those receiving anticoagulant drugs such as warfarin); 8. Female subjects must have a urine or blood HCG negative test (except for menopause and hysterectomy); 9. Subjects and their partners must agree to use effective contraceptive measures during the study until 6 months after the end of the last dose.  Exclusion Criteria:  1. History of severe allergy to mitoxantrone hydrochloride or liposomal drugs; 2. Cerebral or meningeal metastases; 3. History of allogeneic organ transplantation or allogeneic bone marrow transplantation; 4. Life expectancy < 12 weeks; 5. Subjects with chronic hepatitis B (HBsAg or HBcAb positive with HBV DNA ≥ 1000 IU/mL), hepatitis C (HCV antibody positive with HCV RNA above the lower limit of detection of the study center), or human immunodeficiency virus (HIV) antibody positive;; 6. AEs from the previous treatment > Grade 1 based on CTCAE (except for the toxicity without safety risk judged by the investigator, such as alopecia, hyperpigmentation); 7. Active bacterial, fungal or viral infections that require systemic treatment within 1 week prior to the first dose; 8. Local or systemic anticancer treatment within 4 weeks prior to the first dose (within 2 weeks prior to dosing for traditional Chinese medicine or proprietary Chinese medicine); 9. Enrolled in any other clinical trials within 4 weeks prior to the first dose; 10. Thrombosis or thromboembolism within 6 months prior to screening; 11. History of, or known additional malignant tumor within 3 years, except for locally curable tumors that have been cured, such as basal or squamous cell skin cancer or in situ prostate, cervical or breast cancer; 12. Impaired cardiac function or serious cardiac disease:  Long QTc syndrome or QTc interval > 480 ms; Complete left bundle branch block, II-III degree atrioventricular block; Severe, uncontrolled arrhythmias requiring pharmacological treatment; History of chronic congestive heart failure, NYHA ≥ grade 3; Cardiac ejection fraction < 50% within 6 months prior to screening; Heart valve disease with CTCAE ≥ grade 3; Uncontrollable hypertension (defined as a measured systolic blood pressure ≥ 160 mmHg or diastolic blood pressure ≥ 100 mmHg under pharmacological control);  ECG evidence of myocardial infarction, unstable angina, history of severe pericardial disease, and acute ischemic or severe conduction system abnormalities within 6 months prior to screening; 13. Previous treatment with adriamycin or other anthracyclines, and the total cumulative dose of prior adriamycin or equivalent is >350 mg/m2.  14. Pregnant or lactating female; 15. Serious and/or uncontrolled medical condition that, in the judgment of the investigator, may affect the patient's participation in this study (including, but not limited to: diabetes not effectively controlled, kidney disease requiring dialysis, severe liver disease, life-threatening autoimmune and bleeding disorders, substance abuse, neurological disorders, etc.); 16. Not suitable for this study as decided by the investigator due to other reasons.