The petrol-based random copolymer, e.g., aromatic-hydrocarbon resin, is widely used in industrial production, but the research about its gas–liquid two flow is far from being solved. Herein, the formation, motion, and deformation of a single bubble in six different concentrations of random copolymer solutions were systemically investigated using high-speed photography (1000 fps), combined with digital image processing technology. The departure time of the bubble first decreases and then increases, and maximum of aspect ratio and specific surface area reduce as the proportion of solute increases. The bubble departure time decreases and bubble size increases with viscous force increases in the case of same surface tension. Based on force balance analysis, added mass force is one of the prime reasons to affect bubble oscillation during the acceleration phase after bubble detachment, whereas the effect of added mass force decreases as solute increases or as the bubble reaches stability zone. Also, velocity, drag coefficient and aspect ratio of bubble were discussed in detail by dimensionless analysis. Furthermore, three new shape numerical models (based on We, Ta, and WeEo, respectively) were proposed, which allowed for satisfactory predictions, and new correlations represent well the experimental data in a wider range of Mo numbers from the mentioned literature (-11.6 ≤ logMo ≤ 0.63).