Due to the high content of organic matter in weathered coal and differences in physical properties depending on the place of origin, the repeatability of the measurement results is not ideal when using the potassium dichromate oxidation method in the industry standard " Organic Fertilizer" (NY/T 525—2021) to determine the organic matter content in weathered coal. An experimental study is conducted on the influence of sample particle size, moisture content, sample weight, and measurement conditions on the determination of organic matter content in weathered coal from Xinjiang and Inner Mongolia. The results show that after crushing weathered coal through a 0.200 mm sieve and drying to an air dry state, controlling the sample weight to 0.1-0.2 g (organic carbon mass ≤ 80 mg) and shaking the triangular flask every 5 minutes during the oxidation process can accurately determine the organic matter content in weathered coal. The maximum absolute difference of parallel measurement results is ≤ 0.7%, which meets the requirements of NY/T 525—2021, and the organic matter mass fraction measured by the improved method is 7.9% to 9.1% higher than that measured by the method in NY/T 525—2021, indicating that the improved method has a more complete oxidation of organic matter in weathered coal.