The invention discloses a low-voltage transformer area power supply loop abnormity analysis method based on impedance calculation, and relates to the field of power grid power supply analysis. The current electricity stealing condition is difficult to discover, the electricity stealing causes certain loss to an electric power company, one-by-one investigation is carried out by sending manpower tothe field, and the cost is high. The invention comprises the following steps: acquiring ammeter data, when |i1-i0|>s0 and |i1-i0|>s1, then adding the vector into an impedance calculation record table;when the record number in the record table is greater than or equal to the set value n, then deleting the vector with the minimum value of |i1-i0| from the record table to add current vector into therecord table, arranging the record in the sequence from large to small according to the current break variable (|i1-i0|), and calculating impedance, the impedance calculation result=|(u0-u1)|/|(i1-i0)|; and when the calculated impedance value is larger than the impedance set value, analyzing the user. According to the technical scheme, the fault type can be found and positioned in advance, on-site maintenance is arranged in time, the low-voltage loop disconnection fault can be avoided through impedance online monitoring, the equipment fault time is reduced, and the working efficiency and theuser satisfaction are improved.