This paper has investigated the effects of the six factors of concrete volume density, polystyrene particles, water-cement ratio, sand rate, glass powder, and silicon ash on the thermal properties of polystyrene granular concrete, analyzed the degree of influence of various factors through the principal component method, established a comprehensive index where the thermal conductivity of polystyrene granular concrete, is affected by multiple factors and determined a model equation for the standard value of the thermal conductivity. On this basis, the conclusion has been reached. Specifically, the polystyrene particle content has the most significant effect on the thermal conductivity of the polystyrene particles, followed by the bulk density of concrete, with glass powder having the most negligible impact. When the replacement rate of silicon ash is greater than 10%, the thermal conductivity of polystyrene granular concrete could be reduced to improve its thermal performance. When polystyrene granular concrete is prepared using silicon ash, its thermal conductivity is reduced by 22%. When the replacement rate of glass powder does not exceed 20%, it exerts a positive effect on reducing the thermal conductivity of polystyrene granular concrete. Among them, when the glass powder replacement rate is 10%, the thermal conductivity reaches a minimum value, which is 16.1% lower than that of the control group. With the increase of the sand rate, the thermal conductivity of polystyrene granular concrete increases, and the higher the bulk weight of the concrete, the smaller the increase in thermal conductivity.