Swing-piezoelectric energy harvesting has the potential to be used for small-scale tidal and wave energy harvesting. A novel method is proposed to capture tidal and wave energy by combining swing motion and piezoelectric elements in this paper. The dynamic equation and electromechanical coupling equation for the Swing L-shaped Beam Piezoelectric Energy Harvester (SLB-PEH) are derived using the Lagrangian equation, and a Simulink-Adams simulation model is constructed. The model's accuracy is confirmed by comparing theoretical, simulated, and experimental outcomes. Furthermore, key parameters' impact on SLB-PEH performance is examined through experiments. The paper introduces an interleaved SLB-PEH to enhance energy capture efficiency within space constraints. It also describes the design of the Integrated Spring Tidal-Wave Piezoelectric Energy Harvester (ISTW-PEH), which is inspired by the interleaved SLB-PEH structure. The experimental results demonstrate that the ISTW-PEH can generate a maximum power output of 13.6 mW at a flow velocity of 0.3 m/s and a maximum power of 57.6 mW under a wave height of 0.08 m and a wave period of 0.08s.