The invention relates to a three-position conversion switch which comprises a switch shell, a three-position conversion mechanism, an electromagnetic relay switch and a double-dome switch, wherein thethree-position conversion mechanism comprises a push button and a rotary connecting rod. The mobile push button is adopted to drive the rotary connecting rod to rotate and control the sucking close or the separation of an armature sheet and an electromagnetic relay and simultaneously drive a moving dome to joint or separate from a static dome so as to realize the manual and automatic conversion of the three-position conversion switch. Meanwhile, the mobile push button is matched with the double-dome switch so as to ensure that the push button moves, and meanwhile, the rotary connecting rod, the armature sheet and the double-dome switch are linked, thereby better realizing the linking of each mechanism. The invention has artful structure, small size and smooth conversion. In addition, thethree-position conversion switch can realize the conversion of a single-stage or multi-stage circuit as required. Only the numbers of movable contacts and static contacts need to be correspondingly increased, and the conversion of the multi-stage circuit can be realized on the basis of not changing the structure of the prior conversion switch. The invention has wider range of application and stronger compatibility.