In order to study the improvement effect of spent mushroom substrates(SMS)with chemicalfertilizer(HF)on the coastal saline-alkali farmland soil and explore an ecological and efficient improvementtechnology，6 treatments were setup，including:(1)CK；(2)T1(single application of chemical fertilizer，100% HF)；(3)T2(90% HF +10%SMS)；(4)T3(70% HF +30% SMS)；(5)T4(50% HF +50% SMS)；(6)T2(70% HF +30% SMS).The results showedthat the improvement effect of SMS with chemical fertilizer was significantly better than that of CK andT1.(1)Soil physicalproperties:soil bulk density of T3 and T4 treatments significantly decreased by 9.79% and17.48%，respectively( P<0.05)，and soil porosity also increased significantly，compared withCK.(2)Soil chemicalproperties:with the increase of SMS，the soil pH and alkalinity showed a downwardtrend，the cation exchangecapacity(CEC)showed an increasing trend and theCEC content of T5 treatment was thehighest.(3)Soil enzymeproperties:with the increase of the amount ofSMS，the activityof soil urease first increased and thendecreased.The urease activity of T4 treatment was thehighest(1.65 mg·g -1·d-1).At the same time，the invertase activity of T4 treatment was the highest，and increased by 18.19% compared with CK.(4)Soil organic matter and total nitrogen，available phosphorus and available potassium nutrients:compared with CK，the soil organic matter ofT2，T3，T4 and T5 treatments increased by 12.75%～88.68%(P<0.05).With the increase oftheSMS，the content of soil total nitrogen increasedgradually.The content of available phosphorus was the highest(18.5 mg·kg-1)when the amount of SMS was 3582.80 kg·hm -2.There was no significant change in the content of availablepotassium of T2 treatment，but the available potassium in other treatments increased significantly( P<0.05)，and theincreasing order was T4>T3>T5>T1.Therefore，the combination of SMS and chemical fertilizer was agreen，efficient and effective measure for saline-alkali soilimprovement.Comprehensive analysis showed that T4 treatment was the best.