Bioconversion of housefly larvae is a promising method for the value-added recycling of kitchen waste. However, insufficient heat dissipation and oxygen supply limit the substrate intensity considerably, thus necessitating large production areas and enhanced cooling operations. Hence, a net-bottom method is developed to reduce the substrate temperature and improve oxygen supply. For low and high substrate intensities (i.e., 30 and 45 kg/m², respectively), the application of net bottoms decreases the average substrate temperatures by 6.4 °C and 3.9 °C compared with the control, respectively; increases the bioconversion efficiencies by 13.31% and 18.73%, respectively; and increases the relative abundances of aerobic bacteria by 5.93 and 12.94 times, respectively. In addition, the frass yielded by the net-bottom method is conducive to the subsequent aerobic composting. The results of this study are expected to address the challenges of heat dissipation and low substrate intensity indicated in the bioconversion of kitchen waste by housefly larvae.