Abstract: OBJECTIVE To investigate the effects of alveolar lavage combined with immunoglobulin on lung function and immune function in children with severe mycoplasmal pneumonia(SMPP). METHODS Patients were divided into control group and experimental group. Patients in the control group were given small doses of methylprednisolone injection and human immunoglobulin therapy. Patients in the experimental group were given alveolar lavage on the basis of low-dose methylprednisolone and human immunoglobulin injection therapy. The levels of interleukin-2, interleukin-6, and interleukin-10 were measured before and after treatment; and pulmonary vascular resistance(PVR) after treatment, pulmonary capillary wedge pressure (PAWP), mean pulmonary artery pressure(mPAP) and percentage of CD4+, CD8+ in T lymphocyte subsets were measured. RESULTS After treatment, the lung function and immune function indexes of the two groups were significantly improved. The expressions of mPAP, PAWP and PVR in the experimental group were lower than those in the control group(P<0.05). The expression of CD4+, C1D8+ and CD4/CD8 in the experimental group was higher than that in the control group(P<0.05). CONCLUSION Alveolar lavage combined with immunoglobulin and methylprednisolone can significantly improve the expression of inflammatory factors in children with severe mycoplasmal pneumonia, promote the recovery of lung function and improve immune function.