To provide theoretical basis for reducing inorganic fertilizer application during sweet potato cultivation，the effects of different proportions of vermicompost replacing chemical fertilizers on the growth of sweet potato and soil fertility were investigated.The field experiment was conducted with seven treatments:no fertilization(CK)；600 kg/hm² of nitrogen phosphorus potassium(NPK)compound fertilizer(0R)；10% replacement(i.e.:under the same total N application rate as in the 0R treatment，10% of chemical fertilizer N was replaced by vermicompost，10%R)；20% replacement(20%R)；40% replacement(40%R)；60% replacement(60%R)；100% replacement(100%R).The agronomic characters of sweet potato and soil nutrient contents were measured at the root branching-tuberization(40 days after planting)，vine-potato growing(120 days after planting) and harvest(160 days after planting)stages.The yield and quality of sweet potato were analyzed after harvest.Results showed that the agronomic characters(main vine length，stem diameter，leaf length×width，and fresh weight of the aboveground)of sweet potato treated with 40%R were generally better at three stages，followed by 0R treatment.The yields of sweet potato in 40%R treatment(33.65×103 kg/hm²)and 0R treatment(31.51×103 kg/hm²)showed the highest values，which was significantly higher than CK，60%R and 100%R treatments(P<0.05).As the proportion of vermicompost replacing chemical fertilizers increased，the starch and soluble protein contents of sweet potato were firstly increased and then decreased，reached the highest level in the 40%R treatment.The soluble sugar content showed the opposite pattern.During the entire growth stage of sweet potatoes，the soil available nutrients contents of 0R treatment were generally higher，while showed no significant difference compared to 40%R treatment.The soil organic matter content showed the highest values in the 20%R(16.43 g/kg)and 40%R(16.08 g/kg)treatments.The correlation analysis showed a significant positive correlation among soil available nutrients，and a significant negative correlation between starch content and soluble sugar content.Through the PLS-PM structural model，it was found that soil available nutrients had a significant positive impact on sweet potato yield，while the positive impact on sweet potato quality was very weak.However，soil available nutrients contents could indirectly affect sweet potato quality by significantly affecting its agronomic characters.Overall，replacing chemical fertilizer with 40% vermicompost could not only ensure high yield and quality of sweet potato，but also effectively improve soil organic matter content，thus achieve sustainable soil fertility management.