With the development of intelligence and green concepts, triboelectric nanogenerators (TENGs) have gained tremendous attention in wearable devices due to their high sustainability, light weight, and excellent flexibility. However, they may be damaged in high-temperature fires. It is vital to develop a kind of triboelectric material with flame retardance, biodegradability, and high triboelectric properties for the high-temperature alarm and motion monitoring. Herein, a degradable triboelectric material (P/C3P20) with core (polylactic acid/carboxylated multiwalled carbon nanotubes, PLA/C-MWCNT) and shell (polylactic acid/calcium phytate, PLA/PA-Ca) was constructed by coaxial electrospinning. P/C3P20 exhibited burning without molten droplets and self-extinguishing within 6 s, which was due to gas and condensed phases synergistic effects of PO? radicals and the dense char layer. Meanwhile, the P/C3P20 membrane degraded up to 70% on the 4th day in the proteinase K solution. The open-circuit voltage of the P/C3P20-TENG (4 cm², 76.21 V) was nearly 6.1 times that of the casting PLA-TENG. It maintained 71.29% at 160 ℃ and 13.40% at a 520 ℃ flame with burning 20 s, respectively, and successfully outputted stable signals to self-powered sensing. This work provides a novel idea to prepare triboelectric materials and devices with flame retardance, high-temperature resistance, and degradation, which will benefit for early-warning fire and guaranteeing firefights'' safety.