Abstract: According to technical requirements of oil extraction technology in equipments, such as rinsing filter paper, oil-water separation, etc, an equipment to test mechanic admixtures in petroleum products is self-developed and a method with it to determine mechanic admixtures in petroleum products by extraction is presented. The national standard (GB/T 511-2010) method has the problems such as low efficiency, high regent consumption, poor repeatability and reproducibility, etc. The extraction method simplifies the operation, guarantees the experiment precision, and lowers the regent consumption by the cycling equipment with stable structure and enclosed space. Mechanic admixtures in multi-kinds of residual fuel oil are tested according to this extraction method and the national standard method respectively. The results show that the extraction equipment could satisfy the need to test mechanic admixtures and the test value is the same got by the two methods.