In order to study the influence of the distribution of double-layer in-wall coatings with different thickness ratios and up-down orders in the wall thickness direction on the filtration performance of gasoline particulate filter(GPF)，two layers of coatings with different coating amounts were applied in the filtration wall thickness direction，and six different double-layer in-wall coated GPF were formed by changing the up-down orders and thickness ratios. The filtration performance，particle deposition and porosity distribution at the end of filtration of these six GPF and two single-layer in-wall coated GPF were simulated. The results show that the higher the proportion of the coating thickness of the coating with the larger amount of coating to the thickness of the filter wall，the larger the initial filtration efficiency of the GPF，and the upper and lower order of the coatings has no effect on this. The initial filtration efficiency of the GPF increases by 2.50% in the case that the proportion of the coating to the filtration wall thickness increases from 1/4 to 3/4 when a larger amount of coating is located on the top，and the initial filtration efficiency of the GPF increases by 2.52% in the same case when the coating is on the bottom. Both cases of placing a larger amount of coating on the top and having a larger percentage of thickness of this coating enhance the growth rate of filtration efficiency and pressure drop of the GPF during filtration，but the former effect is more pronounced than the latter. For the design of double-layer in-wall coatings，it is recommended to place the larger amount of coating on the top and keep the thickness ratio of the coating smaller，such as 1/4 or 1/2.