In order to clarify the effects of bio-organic fertilizer and shell powder soil amendments and their combined application on soil quality and vegetable quality of vegetable plots in facilities，and to provide technical support for the improvement of cauliflower quality，a three-year field experiment was conducted to set up different application amounts of bio-organic fertilizer，shell powder soil amendments and their combined application treatments.Random forest model was used to investigate the response characteristics of soil properties，microbial characteristics and vegetable quality to amendment application.The results showed that compared with CK，the bulk density of soil treated with double dosage of shell powder soil conditioner(SP2)and combined application of bio-organic fertilizer and shell powder soil conditioner(OF+SP)was significantly decreased(P<0.05)，and double dosage of bio-organic fertilizer(OF2)significantly increased soil alkali-hydrolyzed nitrogen content(P<0.05).All other treatments significantly increased soil pH value(P<0.05).Bioorganic fertilizer and shell powder soil amendments showed a dose effect on soil extracellular enzyme activity to a certain extent.With the increase of application amount of bio-organic fertilizer，soil extracellular enzyme activity showed an increasing trend.However，double dosage of shell powder soil amendment inhibited the activity of soil extracellular enzyme to some extent.Compared with CK，OF+SP treatment significantly increased soil β-glucosidase activity，but significantly decreased soil acid phosphatase activity(P<0.05).Compared with CK，all treatments except SP2 significantly increased soil microbial biomass carbon(MBC)(P<0.05).Double dosage of bio-organic fertilizer(OF2)had the best effect on increasing vitamin C and soluble sugar in cauliflower，which increased by 261.50% and 70.62% compared with CK，respectively.Soil amendment(SP)with conventional dosage of shell powder had the best effect on increasing soluble protein content of cauliflower，which increased by 134.53%，compared with CK.The random forest model showed that β-glucosidase activity，MBC，pH and available potassium(AK) were the key factors affecting vitamin C content in cauliflower(P<0.05).Cation exchange canacity，AK and bulk density were the key factors affecting soluble protein of cauliflower(P<0.05).β-glucosidase activity，pH，MBC，AK were the key factors affecting soluble sugar in cauliflower(P<0.05).Among these parameters，β-glucosidase activity，MBC，pH，AK factor load was higher，which contributed to the improvement of cauliflower quality.Therefore，it was recommended to apply 15000 kg/hm² bio-organic fertilizer and reduce the amount of shell powder soil amendment to improve the soil properties of vegetable plots in facilities，improve the soil microbial biomass and soil extracellular enzyme activity，and then improve the quality of broccoli in facilities.