Abstract: To investigate the effects of co-composting garden waste(GW) with black soldier fly frass(BSFF), five treatments with different mass ratios(GW:BSFF) were tested:T₁(10:0), T₂(9:1), T₃(8:2), T₄(7:3), and T₅(6:4). A 45-day aerobic composting experiment was conducted to systematically monitor the dynamic changes of physicochemical properties during composting, and the maturity of compost products was comprehensively evaluated by the grey clustering method. The results showed that compared with T₁, BSFF addition significantly exhibited faster temperature rise and significantly prolonged the thermophilic phase(≥ 55℃), and both organic matter degradation rate and seed germination index(GI) significantly increased. Among all treatments, T₄ showed the optimal composting performance, characterized by a 15-day thermophilic phase, a maximum temperature of 71.31℃, an organic matter degradation rate of 26.47%, a 36.54% increase in total nitrogen content, and a GI value of up to 108.89%. Both pH and EC value of T₄ met the maturity requirements. Grey clustering evaluation classified the maturity levels of T₁ to T₅ as unmatured, basically matured, well matured, fully matured and fully matured in sequence, with the maturity ranking as T₄>T₅>T₃>T₂>T₁. In conclusion, co-composting GW with BSFF at a mass ratio of 7:3 achieves the best effect and holds great potential for resource utilization.