Objective: To investigate the impact of intergenerational parent-child separation (PCS) on allergic diseases among rural preschool children, providing theoretical guidance for developing targeted public health interventions. Methods: From March to June 2024, 10 kindergartens were selected from Nanling, Wuhu City, Anhui Province. A total of 2 279 children aged 3-6 years and their parents/primary caregivers participated in the survey by a combination of convenience sampling and cluster sampling method. Children s fathers and mothers reported the experiences of PCS during their childhood. The children s PCS experiences and allergies were reported by their primary caregivers. The International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire was used to supplement the allergies (allergic asthma, allergic rhinitis and atopic dermatitis). Analysis of variance (ANOVA) and Chi square tests were used to compare differences between children in different PCS groups. Logistic regression models assessed the association between PCS and the risk of allergic diseases in preschool children. Results: Among the preschoolers enrolled, the prevalence of allergic diseases in only parent-child separation group in childhood, only child separation group, and the intergenerational continuity of PCS groups were significantly higher than those of the none separation group (38.0%, 41.8%, 48.1%,30.4%; χ 2=40.45, P < 0.01 ). After adjusting for covariates including child age, sex and body mass index, Logistic regression model revealed that compared to children in the group without PCS, those in the only parent-child separation in childhood( OR =1.43, 95% CI =1.06-1.94), only child separation ( OR =1.82, 95% CI =1.22-2.71), and intergenerational continuity of PCS ( OR =2.33, 95% CI =1.68-3.24) exhibited higher allergic disease risk (all P <0.05). Conclusions Intergenerational continuity of PCS is related to the increased risk of allergies in preschool children. The multigenerational accumulation of adverse effects from PCS underscores the importance of breaking the cycle of disadvantage across generations.