Objective To analyze the clinical characteristics of the children with severe influenza B and to provide reference for identifying severe cases. Methods Clinical data of 7 children with severe influenza B were retrospectively analyzed. Results The age ranged from 11 months to 7 years old, with an average was (4.13±2.06) years old. Five cases were characterized by respiratory failure, one by cardiogenic shock and one by acute necrotizing encephalopathy. No leukopenia was observed at the beginning of the disease(in 3 days), and the number of white blood cells was as high as 28.1×10⁹/L, White blood cell classification is dominated by neutrophils. haemophilus influenzae and streptococcus pneumoniae were produced by sputum culture in 1 case for each. Three patients had plastic bronchitis changes. After active treatment, the body temperature returned to normal with minimum 2 days, longest 7 days and average (4.20+1.79)days. The length of stay was the shortest 12 days, the longest 23 days, and the average (16.71+3.90) days. Conclusion The clinical manifestations of severe influenza B are diverse and may involve multiple system organs. Respiratory complications were the most common, with plastic bronchitis changes. Early recognition and active treatment had a good prognosis.