Objective To investigate the clinical characteristics, diagnosis, treatment and prognosis of rare simultaneous ipsilateral renal multifocal tumors. Methods The clinical data of a patient with clear cell renal cell carcinoma(ccRCC)and primary renal leiomyosarcoma(LMS)with liver metastasis were retrospectively analyzed. Results The 70-year-old male patient was admitted due to space-occupying lesions of the right kidney detected by physical examination for 12 days. CT showed space-occupying lesions in the upper and middle parts of the right kidney, suggestive of renal cell carcinoma or renal angiosarcoma. He underwent radical nephrectomy. Postoperative pathology showed the tumor in the upper pole of the right kidney with morphology of ccRCC(solid acinar clear cells), but immunohistochemical(IHC)results showed CK(+), EMA(+), CD10(-), PAX-8(-)(rare phenotype); the tumor in the middle of the kidney showed LMS characteristics(spindle cells, active mitosis), Vim(+)and SMA(+). Four months after operation, abdominal CT scan revealed liver metastasis. The biopsy confirmed metastatic LMS, with IHC results showing Vim(+), CD10(+), RCC(+), CK8/18(-), CK7(-), SMA(+), and Caldesmon(+). Subsequently, a liver biopsy combined with microwave ablation of the tumor was performed. The patient was treated with tirelizumab and anlotinib, but the tumor still progressed. The patient died 11 months after operation. Conclusion Simultaneous ipsilateral ccRCC and LMS are extremely rare in clinic, and the prognosis is poor. At present, there is no standardized treatment plan. Surgery is the main treatment for simultaneous multifocal tumors. After surgery, the pathological characteristics of the two tumors should be considered to formulate a comprehensive drug treatment strategy targeting at different biological behaviors so as to provide reference for clinical practice.