The invention relates to the field of direct current transmission, in particular to an implementation method for a direct current transmission system forward direction slope control strategy. A direct current transmission system adopted by the implementation method comprises a rectification side power source, a thyristor valve, a smoothing reactor Ld, a circuit resistor R, a circuit inductor L, a circuit ground capacitor C, a equivalent commutating resistor dxr and a equivalent commutating resistor dxi, wherein the thyristor valve, the smoothing reactor Ld, the circuit resistor R and the circuit inductor L are in sequentially series connection. The implementation method comprises the following steps: A, a constraint function of the direct current transmission system is determined; B, forward direction slope curve volt-ampere characteristics are established; C, voltage fluctuation caused by current deviation is calculated; D, a relation of a turn-off angle and an electric current increment is established; E, a linear function relation of a turn-off angle increment and the electric current increment is established; F, the constraint function is normalized. The implementation method for the direct current transmission system forward direction slope control strategy solves the problem that a stable operation point does not exist between current regulators at two ends and thus direct current oscillates in a reciprocating mode between two definite values, the direct current transmission system can operate stably, and impact to a power grid by power fluctuation is avoided.