Triboelectric nanogenerator (TENG) has a promising future in the field of energy harvesting and self-powered sensing due to their simplicity in structure, low cost, and efficient energy harvesting from the surrounding environment. The output electrical performance of TENG can be improved by doping the friction material with functional materials and modifying the surface of the friction material. However, the current method of adding functional materials to friction materials is costly and wasteful, and the method of modifying the surface structure of friction materials is cumbersome and not easy to operate. In this work, we present a polydimethylsiloxane (PDMS)-MXene/gelatin triboelectric nanogenerator (PMMG-TENG) based on petal surface-microstructures, which has the advantages of low cost, simple preparation, high output performance, and ecological friendliness. By doping 0.03 wt.% of MXene in PDMS, the output electrical performance of TENG can be significantly improved, with an output current increase of up to 139.7%. Four different petals are used as natural molds to prepare PMMG-TENG. The results show that PMMG-TENG with peony petal surface microstructure has the best electrical performance, and the output current increase of up to 228.17% compared with PMMG-TENG without structure. The PMMG-TENG with peony petal surface-microstructure exhibits excellent electrical performance, demonstrating a maximum open-circuit voltage of 417.39 V and a maximum short-circuit current of 12.01 μA at a size of 3 cm × 3 cm, and a maximum power density of 170 μW/cm² at a load resistance of 10⁷ Ω. The PMMG-TENG’s output performance after 10,000 cycles is consistent with the initial state, highlighting excellent output stability. The PMMG-TENG can easily light up at least 100 light emitting diodes (LEDs). (operating voltage 3V.) Gelatin film exhibits excellent degradation performance, with complete degradation time of only 150 s in water at a constant temperature of 75 °C. PMMG-TENG not only shows excellent performance in the field of energy harvesting, but also has a broad application prospect in the field of self-powered sensing. This work provides a simple, low cost, natural and green method to significantly improve the output electrical performance of TENG.