The aim of this study was to investigate the efficacy and safety of pembrolizumab combined with albumin paclitaxel and cisplatin versus albumin paclitaxel and cisplatin or 5-fluorouracil and cisplatin in neoadjuvant therapy for stage II-IVa resectable esophageal squamous cell carcinoma. The study plans to enroll 114 eligible patients who will be randomly assigned in a 1:1:1 ratio to receive 3 cycles of neoadjuvant immunochemotherapy (pembrolizumab plus albumin paclitaxel and cisplatin;Pembrolizumab plus 5-fluorouracil and cisplatin) or chemotherapy alone (5-fluorouracil and cisplatin), followed by surgery 3 weeks later, followed by 16 cycles of adjuvant immunotherapy (pembrolizumab).Patients were followed up for efficacy and safety during treatment.Tumor evaluation will be performed at screening, after neoadjuvant therapy, before surgery, and after adjuvant therapy until objective disease progression is confirmed.