The invention discloses an optimized configuration method of a transformer neutral point capacitor direct-current blocking device. According to the optimized configuration method of the invention, onthe basis of an equivalent field-circuit coupling model, a finite element method is used to calculate the direct-current value of the neutral point of a grounding transformer in a power grid, and therefore, a calculation result is accurate and is close to a measured value; a multi-objective discrete particle swarm optimization algorithm is adopted, and the particle swarm optimization algorithm isimproved with nonlinear reduction inertia weight considering a cosine adjustment coefficient, and therefore, the convergence speed and calculation accuracy of the algorithm can be improved; the inertia weight and adjustment factor are adopted to control the learning factors of the multi-objective discrete particle swarm optimization algorithm, and therefore, the global search capability and localdevelopment capability of particles can be balanced; and a particle update strategy is introduced into the particle swarm optimization algorithm, and therefore, particle update quality and algorithm computational efficiency can be improved. According to the method, the capacitor direct-current blocking device is optimally configured from a global perspective, and therefore, the cost of controllingdirect-current magnetic bias can be reduced, and a control effect is obvious. The optimization algorithm has high calculation precision and high convergence speed, and is suitable for solving practical problems.