Immunoglobulin E (IgE)-mediated egg allergy presents as one of the most common food allergies. The level of specific IgE (sIgE) antibody is widely used as an important diagnostic indicator. However, sIgE antibody levels are often inconsistent with the clinical manifestations of patients. The heterogeneity of egg-specific IgE idiotypes (sIgE-IDs) may help reflect clinical egg allergy severity. Eight peptides were synthesized, corresponding to the linear epitopes of ovomucoid (OVM). The sIgE-IDs of egg-allergic patients were detected by enzyme-linked immunosorbent assay. Fresh peripheral blood was collected from patients with different heterogeneity strength of sIgE-ID, and egg extract was used as a stimulus to the basophil activation test (BAT). RBL-2H3 cells were sensitized with serum with different strength of sIgE-ID heterogeneity and the release rate of β-hexosaminidase was calculated. Among 75 patients with egg allergy, 24% had sIgE for all epitopes and 85% had sIgE for at least one epitope. Analysis of individual patients revealed differences in epitope recognition patterns among the patients, that is, heterogeneity in sIgE-ID. More importantly, the number of IgE-positive peptides had a strong correlation with allergic symptoms in egg-allergic patients ( = 0.706). BAT and RBL-2H3 cell degranulation confirmed that higher sIgE-ID heterogeneity strength was more effective in inducing effector cell responses. Our results suggest that the greater the heterogeneity strength of OVM-sIgE-ID, the more severe the allergic symptoms.