The eustachian tube is a narrow canal which connects the back of the nose with the middle ear cavity.It is made up of a bony component comprising the lateral one third and a cartilaginous component comprising the medial two thirds.The eustachian tube is responsible for three main physiologic functions:①pressure equilibration,②fluid clearance from the middle ear,③protection of the middle ear from pathogens,which help maintain an air filled and fluid free cavity to allow sound transmission.Eustachian tube dysfunction(ETD) is a common middle ear disease which may manifest tympanic membrane atelectasis,otitis media with effusion and attic retraction pocket.ETD is often linked to the underlying possible cause of many middle ear diseases.The diagnosis of ETD relies on the accurate assessment of the Eustachian tube function and different tests have been developed for this intention during the past few decades.In this review we will discuss the application of these tests of Eustachian tube function.