As a renewable and clean energy source, biomass energy is one of the alternatives to traditional fossil energy sources, but its combustion as an industrial fuel produces a large amount of biomass ash with pozzolanic activity, and the study of the regulation mechanism of calcination temperature on the pozzolanic activity of biomass ash can help the efficient utilization of biomass ash. Based on this, we tested and evaluated the pozzolanic activity of willow leaf ash at 500 °C, 700 °C, and 850 °C. The physical and chemical properties of willow leaf ash were tested by XRF, XRD, FTIR, and laser particle size analyzer, microelectrophoresis instrument and other characterization means; The mechanical properties of willow leaf ash-cement based materials after willow leaf ash replaced 30 wt% cement were investigated; the pozzolanic activity characteristics of willow leaf ash were evaluated by strength index, active ion precipitation capacity and pozzolanic reaction efficiency, combined with SEM, XRD, to elucidate the regulation mechanism of calcination temperature on the structural composition and pozzolanic activity of willow leaf ash. The results show that the main oxides of willow leaf ash are SiO2 and CaO, and the compressive strength of willow leaf ash-cement-based material at 500 ℃ is the largest after partial replacement of cement by willow leaf ash, with a strength index of 0.79 and the strongest pozzolanic activity. The absolute values of Zeta potential and conductivity changes of willow leaf ash at 500 °C and 700 °C were greater than those at 850 °C. The Si4+ precipitation concentration decreased with increasing calcination temperature, and too high calcination temperature would lead to slagging of willow ash to affect the pozzolanic activity. This study provides theoretical support for the regulation and application of pozzolanic activity of biomass ash.