This is a single arm, multi-center Phase II Study. This clinical study is an investigator-initiated clinical trial（IIT). The objective of this study is to evaluate the efficacy and safety of Chemoradiationtherapy combined with QL1706 (anti-CTLA-4 and PD-1 antibody) in patients with unresectable locally advanced esophageal squamous cell carcinoma.

Inclusion Criteria:

1. Subjects participate voluntarily and sign informed consent.
2. age:18-75 years, male or female.
3. Histologically confirmed Advanced Unresectable Esophageal Squamous Cell Carcinomas,unresectable of clinical stage II-IVa patients (include unresectable,or surgical contraindication or refuse surgery)(According to AJCC 8th Edition stage , Pre-treatment clinical stage cT1N2-3M0,cT2-4bN0-3M0.
4. At least 1 measurable target lesion and/or unmeasurable target lesion according to Response Evaluation in Solid Tumors (RECIST 1.1).

Exclusion Criteria:

1. Patients who have a history of esophageal cancer surgery.
2. Previous history of fistula caused by primary tumor infiltration.
3. a high risk of gastrointestinal bleeding, esophageal fistula or esophageal perforation.
4. Subjects with poor nutritional status and weight loss of ≥ 10% in the first 2 months of screening have no significant improvement after nursing intervention.
5. Major surgery or serious trauma within 4 weeks before the first use of the study drug.