In practical work, the frequency variation distance protection relay operating characteristics will be impacted by the protection circuit. On the base of the characteristics of the frequency variation protection, this paper analyses the two situations: when there is an equivalent capacitive impedance which is put into the protection’s opposite direction, the system measured impedance will be affected, so that the protection distance is shortened, which will cause the malfunction of the distance protection using power frequency variable components; when there is a short-circuit in the line, the fault current limiter can limit the current lever, but the additional impedance values which brought in by the fault current limiter will not only affects the measurement of the impedance of the relay, but also affects the characteristics of the relay, which will also cause the malfunction of the relay. And a solution of malfunction by resetting the value of setting impedance is offered.