ncreasing the ratio of peak to back (P/B)value is of great importance when using energy dispersive X-ray fluorescence spectrometry to detect heavy metal elements in the light-matrix. Setting up the filters is one way to solve this problem. In the paper the choices (material elements and thickness) for primary filter(it can be divided into One primary filter and Two primary filter) and secondary filter(balance filter) were analyzed, then the Monte Carlo simulation was carried out by MC software, and the accuracy of theoretical analysis was verified by comparing the P/B value before and after setting up. The One primary filter simulation sets up Fe and Cu two kinds of materials. The results show that the biggest P/B values all increases two times after setting up primary filters while the value is 1.36 before setting up; The Two primary filter simulation sets up Te and Ba two kinds of materials. The biggest P/B values are 14.88 and 13.58, which all significantly increase almost 10 times than the previous setting up; The balance filter sets up Rh and Ru two filters, the balancepassband is obtained through two count subtraction. The results show that in the passband the transmission rate of the characteristic peaks is 83.1%, while outside the band the background value is reduced to almost 0, and the P/B values increase greatly. It is found that setting up the three kinds of filters effectively increases the P/B values, in which the balance filter is the most powerful, the Two primary filter is the second, and the One primary filter is the least. The three kinds of filters can be set up at the same time in order to further increase the P/B value in theory, but the Cd amounts in light matrix are trace, so that the low count result will greatly increase the radioactive statistical fluctuation error, therefore, in the practical application, this point should also be considered to decide whether two filters are set up at the same time, or three are set up at the same time. The innovation of this paper lies in the application of the Two primary filter in addition to the traditional two filters.