This study is designed as an open-label, single-arm, single center, phase II clinical trial, aiming to evaluate the efficacy of neoadjuvant Tislelizumab combined with Nab-Paclitaxel for patients with non-metastatic upper tract urothelial carcinoma (UTC). Patients enrolled will receive 2-3 cycles of Tislelizumab in combination with Nab-Paclitaxel every 3 weeks and then undergo radical nephroureterectomy (RNU). The assessment of efficacy is based on the histology of specimen from RNU, and treatment-related adverse events (TRAEs) will be recorded and evaluated according to CTCAE 5.0.