Objective To study the serum immunoglobulin, complement and blood T lymphocyte level and clinical significance in child with persistent pneumonia. Methods The serum immunoglobulin and complement with persistent pneumonia group (63 cases), acute pneumonia group ( 66 cases ) and healthy child group ( 70 cases) were tested by single agar diffusion method respectively,and their blood T lymphocyte percentage were tested by direct immunofluorescence method respectively. The three groups of serum immunoglobulin,complement and their blood T lymphocyte level were analysed using these data. The measured data was analyzsed. Results The persistent pneumonia child group serum IgG[(8.568 ±4.299)g/L]was lower than that in the acute pneumonia child group[( 10. 867 ±3. 012) g/L]and the healthy child group[( 10. 286 ±2.616) g/L]( F =3.86 ,P =0.0245). The persistent pneumonia child group serum IgA[(0.941 ± 0. 336) g/L]was lower than that in the acute pneumonia child group[( 1.281 ±0. 544) g/L]and the healthy child group[( 1.158 ± 0.439 ) g/L]( F =4.57, P =0. 0129). There were no differences among the three groups in the serum IgM,C3 ,C4 and the blood CDs ,CD4/CD8 T lymphocyte percentage(P >0.05).The persistent pneumonia child group blood CD3 (65.629 ± 7.944 )%, CD4 (40. 149 ± 4.633 )% T lymphocyte percentage had differences compared with those in the acute pneumonia child group[( 69. 369 ± 7. 686) %, ( 43. 099 ±5.262)%]and the healthy child group[(71. 842 ±8.266)%, (44.281 ±4.749)%](F=4.78、5.87,P=0.0107、P =0.0040). There were no differences between the acute pneumonia child group and the healthy child group in the serum immunoglobulin, complement and the blood T lymphocyte percentage ( P > 0.05 ). Conclusion The persistent pneumonia child had partly low immune function and immune dysfunction. Key words: Pneumonia; Immunoglobulins; Child