This is a randomized, double-blind, placebo-controlled Phase II/III clinical trial to evaluate the perioperative treatment with QL1706 in combination with neoadjuvant chemotherapy for locally advanced resectable esophageal squamous cell carcinoma. The primary objective of the Phase II is to evaluate the pathological complete response rate of QL1706 perioperative treatment in combination with neoadjuvant chemotherapy for locally advanced resectable esophageal squamous cell carcinoma; the primary objective of the Phase III is to compare event-free survival of QL1706 perioperative treatment in combination with neoadjuvant chemotherapy versus placebo in combination with neoadjuvant chemotherapy for locally advanced resectable esophageal squamous cell carcinoma.

Inclusion Criteria:

• Eastern Cooperative Oncology Group (ECOG) performance score of 0 to 1.
• Patients with thoracic esophageal squamous cell carcinoma diagnosed by pathologic histology or cytology and cT1-2N1-3M0 or cT3-4aN0-3M0 according to AJCC/UICC 8th edition.
• Expected to undergo surgery after completion of neoadjuvant therapy and expected to achieve R0 resection.
• Have not receiv any anti-tumor therapy for esophageal cancer.
• Have adequate organ function.

Exclusion Criteria:

• Significant tumor invasion into organs adjacent to the esophageal lesion;
• a history of gastrointestinal bleeding or those with a high bleeding tendency;
• The presence of supraclavicular lymph node metastases;
• the presence of uncontrollable third interstitial fluid;
• poor nutritional status.