Gallium oxide (Ga2O3) has drawn great attention due to its potential application as a transparent conducting film. However, unavoidable oxygen vacancy (VO) induces the impurity level in the band gap, weakening the transparency of Ga2O3. On the other hand, the VO provides extra electron carriers, facilitating conductivity. Thus, coordinating the relation between the transparency and conductivity becomes rather urgent. Here, we propose that a co-dopant of aluminum (Al) and indium (In), together with oxygen vacancy (AlGa-InGa-VO), is a control method to eliminate the opaqueness and to simultaneously take advantage of the extra electron carriers resulting from the VO. First-principles electronic structure calculations reveal that AlGa with VO (AlGa-VO) does not eliminate the undesirable absorption of VO, whereas InGa-VO does. The defect formation energy of InGa-VO is higher than that of AlGa-VO. Intriguingly, AlGa-InGa-VO not only reduces the defect formation energy but also maintains the transparency of perfect Ga2O3. The strong hybridization between In 4d and O 2p induces the downshift of the impurity level, enhancing the optical bandgap. Our work indicates that doping equivalent elements might provide an effective way to achieve high transparent β-Ga2O3.