Traditional wave energy triboelectric nanogenerators (TENGs) employ multi-directional arrays for omnidirectional energy collection but suffer from bulkiness, structural complexity, material redundancy, and poor weak-wave responsiveness. Herein, a bionic-sunflower-inspired directional adjustment strategy based on a self-adaptive platform is proposed. Driven by the Principle of Minimum Resistance, the platform autonomously aligns toward incoming waves without additional electricity consumption, ensuring the novel Butterfly-Stack TENG (BS-TENG) operates efficiently at optimal orientations. Additionally, the system leverages a lever mechanism to transform low-amplitude, high-torque wave energy into high-amplitude, low-torque kinetic energy, thereby enabling sufficient contact-separation for dense triboelectric layers, significantly enhancing energy utilization under weak wave conditions and boosting charge output by 548% compared to directly floating BS-TENGs. The BS-TENG, fabricated from semi-coated laser-etched Si-Mn spring steel sheets, eliminates internal wiring, frames, and inertia mass. This ultra-lightweight design simplifies fabrication and material consumption, achieving a specific surface area of 6.75 cm² g -1. The working mechanism and output characteristics of the platform are systematically investigated, reaching a max-transfer charge of 13.68 μC per single BS-TENG and demonstrating effective weak-wave energy harvesting for powering multiple electronic devices. This proposed strategy is readily integratable with various wave energy TENGs, offering a scalable and cost-efficient solution for weak wave energy harvesting.