Abstract: Auto manufacturers found that main bearings in automobile engine occasionally produce irregular abnormal noises similar to typewriter sound when the engine is in a neutral idle state. This irregular noise causes panic among consumers and affects the brand image of auto manufacturers. In order to explore the ways to reduce or eliminate this kind of noise, a self-developed parallel plate squeeze oil film test apparatus was used to simulate the oil film noise in main bearings of engine in dynamic load. The testing apparatus can realize the simultaneous acquisition of five signals of sound pressure, displacement, vibration, force and oil film cavitation image, and successfully reproduces the irregular oil film cavitation noise similar to that in main bearing of the engine, and it is found that noise is generated at the moment when the cavitation contacts with the atmosphere. On this basis, from the perspective of practicability and economy, the testing apparatus is used to study the influence of different solid powder additives on the oil film cavitation noise. The article listed carbon black powder, porous aluminosilicate powder, fluorescent agent (oil soluble and non-oil soluble) powder, and molybdenum disulfide powder. The test results showed that carbon powder, porous aluminosilicate powder and non-oil-soluble fluorescent powder had the effect of suppressing oil film cavitation noise. Oil-soluble fluorescent powder had no obvious effect on the oil film cavitation noise and did not reduce the oil film cavitation noise. Molybdenum disulfide powder increased the generation of cavitation noise in the oil film. Among them, the noise inhibitory effect of carbon black powder and porous aluminosilicate powder on the cavitation noise of the oil film initially increased with the increase of its added concentration, but when the concentration exceeded a certain concentration, the noise inhibitory effect gradually stabilized; however, the noise suppression effect of oil-soluble fluorescence powder first increased and then decreased as the concentration increased. After comparing the above three effective solid powder additives, it was found that porous aluminosilicate powder had the best noise inhibitory effect, followed by non-oil-soluble fluorescent powder, and carbon black powder the worst. Their average noise reduction rates were 75%, 70%, 55%, respectively. At the same time, the color of lubricant after adding porous aluminosilicate powder and non-oil-soluble phosphor powder was clear and transparent, which was easier to be accepted by consumers than carbon black powder. Finally, by analyzing the oil film cavitation images when the oil film cavitation noise occurred and the solid powder particle microstructure, it was found that the noise suppression effect of carbon black powder, porous aluminosilicate powder and non-oil-soluble phosphor powder was related to their porous structure. The porous structure had more nucleation points to promote the formation of small bubbles. These small bubbles were not easy to aggregate to form large cavitation, which dispersed the large cavitation and reduced the possibility of the cavitation contacting the atmosphere, thereby reducing the frequency of oil film cavitation noise. The structure of porous aluminosilicate was characterized by dense internal pores and interconnected, which was the reason why it had a better noise reduction effect than the other two. This provided an important method and ideas to solve the irregular noise of the engine main bearing oil film.