The goal of this clinical trial is to learn if immune microenvironment modification could improve the effect of chemoradiotherapy for patients with local advanced esophageal squamous cell carcinoma. The main questions it aims to answer are: 1. Does immune microenvironment could be modified by medium dose of three drugs (paclitaxel, cisplatin, 5-FU), PD1 checkpoint inhibitor, probiotics, and thymosin α1？ 2. Does induction and consolidation of PD1 checkpoint inhibitor improve the effect of chemoradiotherapy for patients with esophageal cancer? This is a single arm study. Participants will: 1. Take one cycle of induction chemotherapy (paclitaxel, cisplatin, 5-FU) and immunotherapy (Sintilimab), two cycle of concurrent chemoradiotherapy, one cycle of consolidation chemo-immunotherapy, and then 1 year of immunotherapy. 2. Take probiotics (Clostridium Butyricum) for 1 year and thymosin alpha-1 daily during radiotherapy.

Concurrent chemoradiotherapy is the standard treatment for patients with inoperable local advanced esophageal squamous cell carcinoma. However, over half of patients will relapse. How to improve effects? We focus on tumor microenvironment transformation by three drug chemotherapy, PD1 inhibitor, probiotics, and thymosin α1，and intent to improve radiosensitivity and reduce recurrence.