Abstract: Objective To investigate the changes of mycoplasma pneumoniae antibody (MP-Ab) and high sensitive C reactive protein (CRP) and their clinical values in the diagnosis of children with mycoplasma pneumonia infection. Methods 110 cases of children with Mycoplasma pneumoniae pneumonia and 120 cases of normal controls children were selected into this study. The MP-Ab and hs CRP levels were detected and MP-Ab titers greater than or equal to 1:160 and hs-CRP>5mg/L were regarded as positive samples. Results The positive rate of MP-Ab and the hs-CRP levels in children with Mycoplasma pneumoniae pneumonia were significantly higher than that of normal controls (P<0.05). The sensitivity of MP-Ab assay for the diagnosis of mycoplasma pneumonia was 78.2%. The sensitivity of MP-Ab combined with hs-CRP assay for the diagnosis of mycoplasma pneumonia was 89.1%, higher than that of MP-Ab detection alone (P<0.05). The specificity of MP-Ab assay alone and combined with hs-CRP assay for the diagnosis of Mycoplasma pneumoniae pneumonia were 94.2% and 89.2% respectively and no  statistically significant beteen them (P>0.05). Conclusion The combined detection of MP-Ab and hs-CRP could have a high clinical value and improve the diagnosis rate of mycoplasma pneumonia in children.