In recent years, inorganic flexible electronics technology has been widely researched as a promising field that enables semiconductor devices to combine excellent electrical and flexible properties for various electronic applications. However, rigid semiconductor materials are susceptible to fracture during service, leading to functional failure. Therefore, mechanical reliability testing is essential for these devices. Digital photoelasticity is one of the techniques that can be used for stress analysis of semiconductor materials, which is a non-destructive, full-field, real-time experimental method based on photoelasticity. In this paper, a transmission-reflection photoelastic combined technique is proposed for internal stress analysis of inorganic flexible electronic bilayer structures. This technique can achieve non-contact, in-situ, parallel measurement of internal stress fields. A transmission-reflection photoelastic bidirectional combined experimental system is developed. A photoelastic parameter extraction technique for stress decoupling of bilayer structures is introduced. An experimental study on the quantitative characterization of the internal stress field of each layer is conducted for a typical class of inorganic flexible electronic bilayer structures.