Coal gasification slag (CGS) is an industrial solid waste rich in silica-aluminum components with latent volcanic ash potential. However, a significant portion of these components exist in a crystalline state with low volcanic ash reactivity. By enhancing its reactivity, CGS can be effectively utilized in large-scale applications, such as mine filling, thus promoting its resource utilization. This study explores the impact of composite excitation using four different excitants on the volcanic ash activity of CGS, employing the response surface method. The compressive strengths of specimens at various time points were measured to calculate corresponding activity indexes, evaluating the volcanic ash activity. A quadratic polynomial regression model was developed to determine the optimal ratio of the four excitants for enhancing CGS activity through multi-objective optimization. The findings indicate that the regression models exhibit strong fitting capabilities, with correlation coefficients close to 1. Sodium silicate primarily influences the 3-day and 7-day activity indexes, while calcium carbide slag significantly affects the 28-day activity index of CGS during composite excitation. Utilizing the Design-Expert software for multi-objective optimization yielded optimal compound excitation ratios: 0.97% calcium carbide slag, 1.61% desulfurized gypsum, 2.55% sodium sulfate, and 10% sodium silicate. Experimental validation demonstrated that the error between predicted and measured values was below 10%.