Abstract: Aiming at reducing the fertilizer amount as well as selecting a green and efficient fertilizer suitable for potato production in arid land of Dingxi area of Gansu province,we conducted an experiment,using a randomized block with five treatments (Conventional fertilizer 1 200 kg·hm^-2(T1); T1+420 kg·hm^-2 fulvic acid fertilizer(T2),70% T₁+420 kg·hm^-2 fulvic acid fertilizer(T3),70% T₁ +300 kg·hm^-2 fulvic acid fertilizer(T4)and CK: no fertilizer),and potato variety Longshu No.6,to discuss the influence of fulvic acid fertilizer for potato root morphology,dry matter,soil enzyme activity and yield.The results showed that the reasonable combination of conventional fertilizer and fulvic acid fertilizer would increase the plant growth,improve soil enzyme activity,and decrease the yield loss caused by continuous cropping.All potato root index showed the best performance with T3 treatment,with a significant difference (P<0.01) compared with CK.T3 and T2 treatments were with greater increasing rates after 70 d compared with T1,T4 and CK.Among them,the dry matter in the underground part under T3 increased by 77.2%-96.7% compared with T1,and 220%-273% compared with CK at 110 d.The potato yield for different treatments was in an order of T3>T2>T4>T1>CK.Urease activity,sucrose enzyme activity and dehydrogenase activity with T3 treatment remained stable.The index of T1 and T4 treatments was higher than that of CK treatment,with a significant difference (P<0.01).Considering the performance of every factor,we recommended that the optimal amount of the combined fertilizer as a base fertilizer would be conventional fertilizer 840 kg·hm^-2+fulvic acid fertilizer (organic matter>45%) 420 kg·hm^-2.