Objective: To investigate the clinicopathological features of basal cell layer type high-grade squamous dysplasia of the esophagus. Methods: Fifty-two cases of basal cell layer type high-grade squamous dysplasia of the esophagus were collected at PLA Joint Logistics Support Force 989 Hospital (34 cases) and Beijing Chaoyang Hospital (18 cases) from 2009 to 2019. The clinical, histological and immunohistochemical features were characterized. Related literature was also reviewed. Results: The median age of the 52 patients was 64 years (range 43-72 years). There were 35 men and 17 women, with a male to female ratio of 2.1∶1.0. There were 8 cases in the upper esophagus, 41 in the middle esophagus and 3 in the lower esophagus. According to the Paris Classification, 24 cases were 0-Ⅱb and 28 cases were 0-Ⅱc. Endoscopic examination showed that the color of the lesions was red and the edge was irregular. The narrow band imaging showed that the lesions were brown, and the microvascular abnormalities on the mucosal surface were observed with high magnification. Iodine staining of the lesions showed no or light staining and irregular border. Histologically, the basal layer of squamous epithelium was hypercellular, with large and hyperchromatic nuclei, and disordered cell arrangement. A high proportion of the cases showed a down-growth pattern and associated invasive squamous cell carcinoma. The immunohistochemical staining of 37 cases showed that the mutation rate of p53 was 48.6% (18/37), the median of Ki-67 labeling index was 60% (range 20%-90%), the median of Ki-67 labeling index of the basal tumor cells was 26/HPF (range 5-70/HPF), and the rate of abnormal Ki-67 distribution pattern was 37(100.0%). According to the initial pathological diagnosis, there were 8 cases of low-grade intraepithelial neoplasia, 2 cases of atypical epithelial cells and 42 cases of high-grade intraepithelial neoplasia. Conclusions: The basal cell layer type high-grade squamous dysplasia of the esophagus has a unique morphology. The dysplasia is mainly limited to the lower half part of the squamous epithelium. With marked cytological atypia and prominent invasiveness pattern, it is likely to develop into invasive squamous cell carcinoma at an early stage of the disease. The rate of pathologic misdiagnosis (such as low-grade lesion) is high. The p53 mutation and Ki-67 abnormal distribution pattern are helpful features for confirming the diagnosis of such high-grade dysplasia.