A high-power single-mode semiconductor laser with photonic crystal structure is demonstrated. The high-order surface gratings are designed as longitudinal photonic crystals to introduce distributed reflection defects. A broad ridge is employed to enhance output power, accompanied by two sets of transverse photonic crystals on either side to filter out high-order lateral modes. At an injection current of 700 mA, the output power of the laser reaches 120 mW, featuring a single-flap horizontal far-field (HFF) distribution with a full width at half maximum (FWHM) of only 8.8°. The lasing wavelength is 1.3 μm with a side-mode suppression ratio (SMSR) up to 41.74 dB. The fabrication process is based on standard lithography, avoiding the need for high-precision lithography and regrowth techniques, providing a cost-effective and simple-process solution for single-mode lasers.