The effects of ethylene glycol， triethanolamine and polycarboxylic acid as grinding aid on the particle characteristics of sugarcane bagasse ash（SCBA） were investigated， the mechanism of the particle characteristics of SCBA on the microstructure of mortar was clarified， and the correlation between SCBA particle characteristic and mortar strength were analyzed. Based on the relationships between water-cement ratio， SCBA content， particle characteristic， and compressive strength of mortar， a multi-factor model for compressive strength of SCBA mortar regulated by particle characteristics was established. The results show that incorporating 0.08% triethanolamine optimizes the particle characteristics of SCBA to the maximum extent. Excessive content and large specific surface area of particles with a diameter D≤3 μm negatively impact SCBA mortar strength. To enhance SCBA mortar strength， increasing the content of particles with 3 μm<D≤32 μm and decreasing the content of particles with D≤3 μm and D>32 μm are recommended.