The WHO classification of esophageal tumors divides esophageal squamous intraepithelial dysplasia into high and low grades, but does not specify its morphological spectrum. Here, the morphological characteristics of various cells were investigated in esophageal squamous (high-grade) dysplasia, and a morphological spectrum and terminology for this lesion were proposed to avoid misdiagnosis. The clinicopathological data of 540 patients with esophageal squamous dysplasia were analyzed retrospectively. According to the unique cytomorphological characteristics of the lesions and the predominant cell type, the esophageal squamous dysplasia was divided into the following morphological groups: classic type (34.6%, 187/540), basaloid subtype (10.7%, 58/540), spindle-cell subtype (4.6%, 25/540), differentiated subtype (48.9%, 264/540), and verrucous subtype (1.1%, 6/540). Gender, age, and lesions location did not differ among the subtypes (P > 0.05), while Paris classification and lesions diameter significantly differed among the subtypes (P < 0.01). Classic-type cells showed severe atypia. In the basaloid subtype, the cells were small, and resembled basal cells; most of these lesions were of the 0-IIb type with small lesion diameter. In the spindle-cell subtype, the cells and nuclei were spindle-shaped or long and spindle-shaped and arranged in parallel. Differentiated-subtype showed well-to-moderately differentiated cells, and epithelial basal cells were mature. Verrucous-subtype showed well-differentiated cells, and were characterized by verrucous or papillary structures. Esophageal squamous dysplasia has extremely wide morphological spectrum. Awareness of the spectrum of morphological presentations of this lesion, specifically the basaloid subtype, spindle-cell subtype, differentiated subtype, and verrucous subtype, is important for accurate diagnosis.