Otitis media with effusion is one of the most common childhood diseases. Inspite of numerous investigations on the subject, its pathogenesis still remains obscure. The inflation and deflation test is one of eustachian tube function test. Strictly it is test of active dilatory function of eustachian tube. As opening pressure. We can detect the patency of eustachian tube. Ventilation tube appeared effective in normalizing the pathologic mucosa and reducing the secretory cell on middle ear of OME. So we analysis the data of 24 SOM patients(48 ears)with deflation and inflation test after ventilation tube insertion and adenoidectomy. We conclude that there was no significant change of residual pressure after ventilation tube insertion and adenoidectomy in SOM patients.