In this paper, a frequency up-conversion piezoelectric energy harvester based on a type of spring vibration platform is proposed to solve the problem of low efficiency of low-frequency vibration energy harvesting. The cubic positive correlation between the output power of piezoelectric cantilever beam and the excitation frequency is analyzed, and the reason for harvesting low frequency vibration energy by up-conversion is explained. The Hertzian contact theory is used to analyze the contact-force between the plucking plate and the piezoelectric cantilever beam, and the electromechanical coupling model of the piezoelectric energy harvester with the plucking excitation is established. After comprehensively considering the influencing factors of the overlapping length and the thickness of the plucking plate, the rectangular stainless steel plate with a thickness of 0.1 mm is selected. The experiment shows that the output power of the single-plucking up-conversion V25W piezoelectric cantilever beam can reach 9.6 mW under the excitation of 1g(g=9.8 m/s2） and 5.67 Hz, which has strong low-frequency energy harvesting performance.