The qualified degree of line loss is an important standard to evaluate the performance of substations.The wrong wiring of watt-hour meters has a great influence on the calculation of line loss.There are many kinds of wrong wiring ways of watt-hour meter,and it is very complicated.Only combining with the actual situation can we make a correct judgment,draw a corresponding conclusion,and improve the stable and economical operation level of substation.Through analyzing and judging a lot of data of typical cases,the problem of abnormal bus level loss caused by wrong wiring of watt-hour meter is studied.