This is a randomized, placebo-controlled, multi-center, double-blinded, Phase III study to determine the efficacy and safety of patients with locally advanced squamous cell carcinoma of the thoracic esophagus treated with perioperative immunotherapy combined with neoadjuvant chemotherapy versus placebo combined with neoadjuvant chemotherapy.

Patients must fulfill all of the following inclusion criteria to be eligible for enrollment in this study:

1. Histologically confirmed locally advanced (T1N1-3M0 or T2-3N0-3M0) squamous cell carcinoma of the thoracic esophagus (per the 8th Edition of UICC-TNM Classification);
2. No suspicious cervical lymph node metastasis on cervical contrast-enhanced CT; no systemic metastasis from radiological examination;
3. Expected to be achievable to conduct R0 resection.

Patients must not enter this study if any of the following exclusion criteria is fulfilled:

1. Having malignant tumors other than esophageal carcinoma within 5 years prior to randomization;
2. Combined with other inoperable condition;
3. Previous serious allergy to chemotherapeutic agents (paclitaxel or cisplatin) or any monoclonal antibody;
4. Combined with other conditions unsuitable for participation in this study as judged by investigators.

Other protocol defined Inclusion/exclusion criteria could apply.