To solve the optimization problem of the position and quantity of dampers in spatial structure， a new coding method， “A-B”type digital coding， was proposed based on a genetic algorithm， which realizes the precise positioning of the optimal arrangement of dampers. The additional stiffness and damping matrix of the magnetorheological damper （MRD） were deduced， the improved genetic algorithm was proposed by adopting the H2 norm optimal control theory and the intergenerational comparison weight， and the multi-objective spatial optimization arrangement was used to develop the improved genetic algorithm program using MATLAB software. Taking a ten-story reinforced concrete frame-shear wall eccentric structure as an example， seven seismic waves were selected as dynamic time history input according to the specification， the structural displacement， acceleration， and torsion control under an optimization scheme， and three working conditions were calculated， and the development trends of different shock absorption indexes with the number of MRDs were analyzed. The results show that the value of the optimization objective function converged rapidly with the evolutionary algebra. The optimization scheme has the best control effect in the four working conditions， the shock absorption rates in the X and Y directions of the No. 88 node on the top floor reached 39.45% and 36.48%， respectively， and the structure torsion was effectively controlled. The numerical example showed the effectiveness of the improved genetic algorithm， the precise positioning of the damper arrangement of the space structure is realized， and the structure is optimally controlled.