Dominant 794nm wavelength upconversion emission, which originates from the Tm3+: 3H4®3H6 transition, has been recorded in Tm3+/Yb3+ codoped aluminum germanate glass under the 974nm wavelength laser excitation. Judd-Ofelt parameters W2 (6.52´10-20cm2), W4 (9.83´10-21cm2) and W6 (1.02´10-20cm2) indicate a higher inversion asymmetric and stronger covalent environment in the glass material. The spontaneous transition probability of 3H4®3H6 was derived to be 1121s-1, which is responsable for obtaining the powerful 794nm emission. K+-Na+ ion-exchanged multimode channel waveguide amplifiers have been fabricated based on the Tm3+/Yb3+ codoped aluminum germanate glass substrate. The relative gain coefficient of a 2.20cm channel waveguide was determined to be 1.58dB/cm at a signal wavelength of 810 nm under 457mW 980nm laser diode excitation.