Abstract: OBJECTIVE To investigate the relationship between recurrent respiratory tract infection (RRTI) in children and the serum immunoglobulin, IgG subclasses and cellular immunity level changes, so as to provide the pathogenesis of RRTI in children. METHODS A total of 32 children outpatients and inpatients diagnosed as RRTI from Feb. 2012 to Jun. 2014 were selected as RRTI group; over the same period 27 children in outpatients and inpatients treatment of acute respiratory infection were selected as the group of infection; and another 35 healthy children in 1~4 years old were selected as control group. The immunoglobulin indexes were compared in these three groups and data were analyzed by SPSS 17.0. RESULTS The CD₃⁺+, CD₄⁺, CD₄⁺ / CD₈⁺ and CD₁₉⁺ expression levels of three groups had significant difference (P < 0.05). Detection rate of IgG subclasses deficiency in children with RRTI was 46.88%. The highest individual defection rate was IgG4, accounting for 40%, defection rate of IgG2+IgG4 was the highest, which was 26.67%. CONCLUSION The cause of recurrent respiratory infection has close relation to humoral immunity and (or) cells immune function disorders; IgG subclasses (IgG2, IgG4) can be used as a sensitive indicator of immune function in recurrent respiratory infection children, which should be paid attention to the monitoring of serum IgG subclasses and the cellular immune function in patients.