<p>Nickel-based superalloys are critical for high-temperature aerospace components, owing to their excellent mechanical strength and oxidation resistance. However, their poor ductility and tendency to form brittle phases make them highly susceptible to cracking during laser powder directed energy deposition (DED). This study investigates the influence of DED process parameters on the morphology and defect of K477 alloy. Based on single-track experiments, support vector regression was used to correlate key process parameters (laser power, scan speed, and powder feed rate) with morphological characteristics (width, height, wetting angle, dilution rate) and quality metrics (density and shell-like defect count). The SHapley Additive exPlanations model (SHAP) was applied to quantify the sensitivity of each process parameter. A multi-objective optimization approach was then used to minimize defects and maximize density within acceptable morphology ranges. Utilizing the optimized process parameters, bulk samples are successfully fabricated with a density up to 99.41%, and their ultimate tensile strength are improved by 15.8% compared to the cast alloy. Although no macroscopic cracks were observed, microscopic defects such as gas pores and shell-like defects remain challenging to fully eliminate. Microstructural and elemental analyses indicate that shell-like defects, primarily enriched in Al and O, can be effectively mitigated through refined process control.</p>