For the significance of positive and negative Mycoplasma pneumoniae, the focus is on determining the presence or absence of Mycoplasma pneumoniae infection. Mycoplasma pneumoniae antibody can be divided into IgG antibody and IgM antibody, clinically Mycoplasma pneumoniae positive usually refers to the IgM antibody is positive, can be used as a judgment of acute infection of Mycoplasma pneumoniae, IgM antibody is negative, IgG antibody is positive can suggest that the previous infection of Mycoplasma pneumoniae, both are negative suggests that there may be no infection of Mycoplasma pneumoniae. However, it should be noted that negative IgM antibody cannot exclude Mycoplasma infection, because IgM antibody may be absent in re-infection. Therefore, it is usually necessary to combine the clinical symptoms, Mycoplasma pneumoniae antibody test, chest X-ray, urine routine, etc., to diagnose the presence of Mycoplasma pneumoniae infection.