Objective: Study of infectious mononucleosis in infants and children using eb-virus serology and joint DNA analysis.Methods: Select 82 cases of infectious mononucleosis in infants in our hospital in January 2023-april 2024, when elisa tested antibodies in infected children using PCR to determine ebv-dna weights.Results: The positive rate of VCA-IgM in acute phase, recovery phase and follow-up period is increasing with the age of patients. Correlation analysis showed that the detection results of VCA-IgM, VCA-IgG and EBV-DNA were positively correlated with the patients" diseases, which was significant (P < 0.05). The results of ROC diagnosis showed that the AUC of VCA-IgM, VCA-IgG and EBV-DNA in the diagnosis of infectious mononucleosis in infants was 0.547, 0.915 and 0.693, and the AUC of combined diagnosis was 0.983.Conclusion: Infectious mononucleosis of small and small children with low serum content was diagnosed by serum method and a combined analysis of ebv-dna weights with higher value was recommended.