To avoid the circumstances that the maloperation currently occurs when the wide-area current differential protection is influenced by the capacitive current, this paper improves the traditional current differential protection and puts forward a way to calculate the wide-area current differential protection that is not affected by capacitive current. We use differential equation to calculate the capacitive current on different circuits, and by using amendatory differential current, we make efficient compensation for fault transient current and steady capacitive current. That is to guarantee current differential protection against the influence from capacitive current, we subtract the calculated capacitive current from the traditional differential current. The PSCAD simulation experiment compares this protection with the traditional current differential protection. It turns out that this protection is not affected by capacitive current, and has no maloperation through external failure, which verifies the feasibility and effectiveness of this protective calculation.