Abstract: Abstract: As of 2020, Chinese food waste was about 120 million tons, which increased by 5.80% over 2019 and will continue to increase. The auxiliary heating bio-drying technology is an ideal method for the ‘reduction, harmlessness and resource utilization’ of food waste. The drying products can be returned to the soil as fertilizer or soil conditioner. In recent years, the problem of soil sulfur deficiency in China has become more and more serious. Sulfur is an essential nutrient element for plant growth and development, and the demand for sulfur is equivalent to phosphorus in agriculture. There is a large amount of sulfur lost in the form of H2S during the process of drying, these pungent odors can endanger human health and pollute the environment. In order to effectively control the H2S emission in the bio-drying process of food waste and retain the sulfur nutrients in the drying products, the sulfur transformation during the food waste auxiliary heating bio-drying process was studied under different ventilation modes (continuous ventilation (CAR) and intermittent ventilation (AR)) and different ventilation rates ( 0.25, 0.50, 0.75 L/(min·kg) ). In all six ventilation treatments, the food waste and sawdust were mixed in 7:1 (wet weight), and the C/N ratio was adjusted to 16. An auxiliary heating bio-drying experiment was conducted for 15 days in a closed cylindrical reactor with a total volume of 55 L. Multipoint mixed samples were collected on days 0, 3, 6, 9, and 15 of the bio-drying process. The basic physicochemical, maturity indexes and sulfur component indexes were measured, including temperature integration (TI), pH value (pH), electrical conductivity (EC), seed germination index (GI), moisture content (MC), total carbon (TC), total nitrogen (TN), total sulfur (TS), volatile solid mass (VS), water-soluble sulfur, adsorbed-sulfur, and HCl-soluble sulfur. H2S emissions were continuously monitored daily. Pearson correlation analysis was also used to analyze the correlation between different sulfur components, as well as different sulfur components and physicochemical parameters. The results showed that at the end of bio-drying, the temperature integration (606.60℃) and seed germination index (100.00%) of AR0.5 treatment were the highest, and the moisture content (38.05%) was the lowest. The intermittent ventilation rate of 0.50 L/(min·kg) benefits the pile’s heating, dehydration, and maturity. Correlation analysis showed that the cumulative emission of H2S was significantly positively correlated with water-soluble sulfur (P<0.01) and significantly negatively correlated with HCl-soluble sulfur (P<0.01). HCl-soluble sulfur in AR0.25 and AR0.5 treatments decreased the most, which was 83.93% and 79.23%, respectively. And the increment of water-soluble sulfur was 337.06, 585.36 mg/kg. It can be seen that intermittent ventilation rates of 0.25, 0.50 L/(min·kg) are propitious to the mobilization of HCl-soluble sulfur and accumulation of water-soluble sulfur, but the cumulative emission of H2S also was the most, reaching 123.60 and 103.00 mg/kg, respectively. The cumulative emission of H2S decreased with the increase in ventilation rate, as well as that of continuous ventilation was lower than intermittent ventilation. When the ventilation rate was less than 0.50 L/(min·kg), the total sulfur loss increased with the increase in ventilation rate. Otherwise, the total sulfur loss decreased with the increase in ventilation rate. The total sulfur loss of CAR0.75 treatment was 3.46% lower than that of AR0.75. Therefore, the comprehensive evaluation of a continuous ventilation rate of 0.75 L/(min·kg) is conducive to sulfur retention and H2S emission reduction during the auxiliary heating bio-drying process.