A method based on fault transient process for coordinating operating characteristics of a differential relay comprises the steps that: the current sampling values of braches of each bus are obtained through AC (alternating current) sampling; the positions of switches on the branches of each bus are obtained; differential current on two buses, differential current on the bus I, and small differential current on the bus II are calculated according to bus connecting manner and the positions of the switches on every branch; and if the buses are in the dividing sate, the large-differential proportional brake coefficient is reduced to 0.3. The method can ensure that bus can act reliably at every area where fault happens.