The invention discloses a single tube-inserting connecting structure of steam outlet connecting tubes of a steam generator of a high temperature gas cooled reactor. The structure comprises a steam outlet tube plate 1, a spiral heat exchange tube 3 and steam outlet connecting tubes 2, wherein one end of each steam outlet connecting tube 2 is connected to the steam outlet tube plate 1 while the other end of each steam outlet connecting tube 2 is connected to the spiral heat exchange tube 3; each steam outlet connecting tube 2 comprises a plurality of straight sections and a plurality of transitional elbows; each steam outlet connecting tube 2 connected to the steam outlet tube plate 1 can rotate along an axis of a tube orifice; and all transitional elbows on each steam outlet connecting tube 2 are arranged in a vertical plane. The structure disclosed by the invention fills the blank of the field, so that single tube insertion is realized, and the tube-inserting difficulty and risk are reduced. Moreover, the plurality of groups of steam outlet connecting tubes connecting a tube bundle 7 are arranged in a limited space, so that requirements on flow-induced vibration, thermal stress, welding, assembly and the like are satisfied.