The invention discloses a processing method of black-core playing card paper, which is characterized in that in the pulping process of base paper, black dyes are added in core pulp, and simultaneously trivalent aluminate is added simultaneously and stirred uniformly. The processing method has the advantage of improving affinity of the black dyes and wood fiber in the core pulp due to adding the black dyes and the trivalent aluminate into the core pulp simultaneously, leading the black dyes in the core pulp not to flow into water in the process of paper making and forming of a paper machine, avoiding a wite section of the paper machine from being polluted and ensuring that only the core layer in the processed playing card paper is black. In addition, the method has simple processing, is suitable for large-batch production and has lower production cost.