Surface-mode resonance coupling effect and high-temperature sensing characteristics of hollow-core photonic bandgap fibers are proposed and studied herein. The surface-mode coupling effect in the photonic bandgap fibers was observed experimentally, and the generation principle of the effect was theoretically explained. Multiple resonance peaks were formed in the fiber transmission spectrum, were subjected to temperature- and strain-sensing experiments, and unique temperature and strain sensing characteristics were observed. The resonance peak was insensitive to low temperatures between 20 ℃ and 150 ℃, whereas it was sensitive to high temperature between 150 ℃ and 260 ℃. This temperature sensitivity observed between 150 ℃ and 260 ℃ reached -0.26 dB/℃. Simultaneously, the wavelength of each part was insensitive to temperature, and the intensity and wavelength of the resonance peak were insensitive to strain. The hollow-core photonic bandgap fiber sensor addressed the temperature-strain cross-sensitivity problem, effectively can realize real-time intensity detection in a high-temperature environment, and has many advantages, including a simple structure and ease of use.