The rational layout and scientific configuration of public cultural space is an important criterion to measure the public service function of a city, whether it is perfect or not. In this paper, Hohhot Downtown is selected as the research object, and the spatial layout structure of the city is explored using the indicators of expansion intensity, compactness and fractal dimension. A layout optimization method based on a genetic algorithm is proposed to build a spatial layout model, set the spatial layout optimization constraints, complete the genetic algorithm optimization through the optimization coding process, and finally solve the Pareto optimization solution set by using the genetic algorithm of Matlab, which results in the optimization scheme of the new public cultural spatial layout of Hohhot City. The results show that six new public cultural space layout schemes of Hohhot are obtained after optimization, and the six layout scores are in the interval of [0.9, 1.0], all of which are excellent. Decision makers can choose the final layout scheme based on their actual situation and decision preferences.