Abstract: Bromine exists mainly as ions in bromide brine and halide sulfate brine in the hydrosphere of the crust. Powder carrier pellet method is commonly used in analyzing bromine in brine by Wavelength Dispersive X-ray Fluorescence Spectrometry (WDXRF). However, this sample preparation method has the disadvantages of large work load, sample inhomogeneity and outer contamination, which affects the analytical accuracy. Samples were pretreated by film adsorption, and film material and sample weight were optimized and are reported in this paper. Firstly, 50 μL of brine is dropped to the center of a chromatography filter paper (Ф=40 mm), air dried, and then flattened by high pressure to prepare the film sample for WDXRF test. A standard curve of Br was calibrated by self-prepared standard solution. Experimental results show that the impact of coexisting ions such as K⁺, Na⁺, Ca²⁺, Mg²⁺, Cl^- and SO₄^2- on the detection of Br is negligible. The detection limit of this method is 0.95 mg/L, the precision is less than 0.8% (n=11), and the recoveries are 99.4%-101.2%. The new sample preparation method is very economical and easy to operate, avoiding the use of chemical reagent.