OBJECTIVE: To explore the diagnosis and treatment of small kidney cancer, and to provide clues for further research on the treatment of small kidney cancer with preserved kidney units. METHODS: We retrospectively analyzed 60 cases of small kidney cancer with diameter ≤4 cm, analyzed the clinical characteristics of small kidney cancer and its combined diseases, compared the characteristics and roles of ultrasound, CT, MRI, DSA, IVP and ECT in the diagnosis of small kidney cancer, and followed up the effects of various surgical treatments. RESULTS: The accuracy of ultrasound, CT, MRI and DSA in diagnosing small kidney cancer was 85.7%, 96.3%, 82.3% and 100%, respectively, while IVP and ECT could only be used as adjuvant examinations. All 60 patients underwent surgery, including 6 cases of renal tumor enucleation, 3 cases of laparoscopic surgery, 3 cases of intraoperative frozen pathological examination before nephrectomy, 2 cases of renal tumor enucleation, postoperative pathology reported as renal cancer, and 1 week after surgery, nephrectomy was performed again, 14 cases of radical nephrectomy and 32 cases of simple nephrectomy. Pathological diagnosis: 50 cases of clear cell carcinoma, 1 case of granular cell carcinoma, 6 cases of mixed type (clear cell carcinoma + granular cell carcinoma), and 3 cases of other types. Forty-six cases (76.7%) were followed up for 3 months to 7 years. There were 14 cases surviving for 5 years after surgery. Conclusion: Ultrasound, CT and MRI are the most common and accurate methods to diagnose small kidney cancer, more small kidney cancer needs to be combined with DSA examination and pathological examination, and the treatment method of preserving kidney unit is the trend of small kidney cancer treatment.