Bioconversion using insect larvae has proven to be a feasible option for food waste disposal and has generated products with high economic value. Technological optimization can further improve costs and applicability. In this study, the effects of different substrate intensities and feeding methods on housefly larvae bioconversion were investigated using the solid-phase fraction of kitchen waste obtained after a three-phase separation as the raw material. The results showed that a substrate intensity of 30 kg/m² combined with one-time feeding was the most appropriate. Under these conditions, an appropriate substrate temperature prevented the escape and early pupation of larvae, and the bioconversion and reduction rates of kitchen waste reached 16.75% and 50.51%, respectively. In addition, the physical and chemical properties of frass were found to be conducive to subsequent aerobic composting.