The incidence of adenoid hypertrophy in children with allergic rhinitis is higher than that in children with non-allergic rhinitis, and the incidence in children with allergic rhinitis has gradually increased in recent years. We consider that post-adenoidectomy occipital hyperplasia may be closely related to allergic rhinitis. Perennial allergic rhinitis may be the main cause of post-adenoidectomy occipital hyperplasia, and chronic rhinitis or chronic sinusitis that persists is also an important cause. Allergic rhinitis is an important risk factor for adenoid hypertrophy. The adenoids and tonsils are the lymphoid tissues closest to the nasal mucosa in humans, and studies have found that allergen-related lymphocytes and cytokines are higher in the adenoids of children with allergic rhinitis than in those with non-allergic disease. After adenoidectomy, lymphocytes in the nasopharynx, mainly in the round occipital tissue, can proliferate reactively in response to allergen stimulation. The round occipital mucosa is a continuation of the nasal mucosa, and its structure is basically the same as that of the nasal mucosa. When allergic rhinitis occurs, the basement membrane of the round occipital mucosa thickens due to the increase of glands in the lamina propria and the accumulation of a large number of inflammatory mediators, which can also thicken the edema of the round occipital mucosa. In this group of cases, not only the round occipital area was hyperplastic, but also the residual adenoid tissue was hyperplastic in some cases. Pathological examination confirmed lymphocyte hyperplasia, increased glandularity, and thickened basement membrane edema in the hyperplastic occipital mucosa. In order to prevent the postoperative hyperplasia of the round occipital and residual adenoid tissue in children with adenoid hypertrophy combined with allergic rhinitis, routine antiallergic treatment, especially nasal spray glucocorticoids, should be used after adenoidectomy to reduce round occipital edema and hyperplasia.