The workspace Measuring and Positioning System (wMPS) is an indoor large-scale positioning system based on the intersection of laser planes.Station network layout is a system of structural factors that directly affects the system measuring accuracy.To get a better layout, we analyzed the measuring equation of the system and pointed out that the condition number of measurement matrix can be a quantitative indicator to planes intersection and gave the mathematical model.The optimum network layout was achieved with the Genetic algorithm which was designed based on the quantitative indicator.The experimental results show that this method can effectively improve the measurement precision.