The biomechanics of insect jumping has long been a focal point in entomological research, with prior investigations predominantly characterizing the locomotive performance of adult insects. However, the developmental trajectory of leaping capabilities across ontogenetic stages remains poorly understood, particularly for species exhibiting significant morphological and behavioral plasticity. This study addresses this knowledge gap by systematically analyzing the developmental progression of jumping ability in Lycorma delicatula (Hemiptera: Fulgoridae), an invasive phytophagous planthopper with remarkable adaptive locomotion strategies. Through a combination of high-speed videography, micro-computed tomography (μCT) scanning, and kinematic analysis, we quantitatively compared the morphological structures and biomechanical parameters of both nymphal and adult stages. Our results revealed a 3-fold increase in hind femur length from fifth-instar nymphs to adults, accompanied by a 4.2-fold enhancement in takeoff velocity. Notably, while nymphs exhibited a "short-distance burst" jumping pattern with limited aerial control, adults demonstrated a more sophisticated ballistic trajectory with extended flight duration and precise landing orientation. Morphometric analysis further identified allometric growth in the trochanter–femur–tibia linkage system, with the protraction–retraction angle expanding from 32° in nymphs to 58° in adults. These findings suggest that the developmental refinement of jumping ability in L. delicatula follows a two-phase adaptation model: initial survival-oriented short-range jumps in early instars transition to energy-efficient, long-distance leaps in mature adults. This study provides novel insights into the ontogenetic biomechanical evolution of insect locomotion, with implications for understanding both developmental plasticity and ecological invasiveness in hemipteran pests. The phase-specific optimization of jumping mechanisms, particularly the synergistic relationship between morphological scaling and kinematic efficiency, offers valuable biomimetic principles for designing bio-inspired micro-robotic systems.