Bubble condensation with non-condensable gas is more common than pure steam bubble. In this study, a systematic experimental investigation on the air-steam bubble condensation with comparatively large ranges of the liquid subcooling from 10 K to 70 K and different initial mole fractions of non-condensable gas <0.3 are carried out. Results show that the air-steam bubble trends to condense as a whole when the initial mole fraction of non-condensable gas x0 is >15%. When x0 is <15%, the pattern transition from bubble shrink to split can be observed and the values of x0 corresponding to this transition trend to increase with the increasing liquid subcooling. A similar phenomenon can also be found in the pattern transition from bubble split to collapse. Meanwhile, three typical bubble breakage processes are observed and identified, which are named as flatten-, stretch- and shrink-breakage. Moreover, a new Nusselt number correlation is proposed which is related to bubble Reynolds number, Prandtl number, Jacob number and x0. After comparison, our correlation can predict well not only the results in this study but also the data-sets of air-steam bubble condensation given in the literature, which shows good performance in robustness. •A systematic experiment on air-steam bubble direct contact condensation is proposed.•Three typical bubble breakage processes are firstly observed and identified.•A regime map on the bubble deformation in the condensation process is presented.•A new correlation of Nusselt number is given with a larger range of subcooling.•Our correlation can predict well the data of this study and those in the literature.