Abstract: The influence of emulsifier, soap solution pH value, storage time, storage temperature on the particle size and stability of bitumen emulsion was investigated by means of laser particle size analysis and residue content difference tests. The correlation degree between stability/particle size and various factors was analyzed based on the gray relation theory, and the correlation between stability and particle size was also investigated. Results show that there are good correlations between the influencing factors with the particle size and stability of bitumen emulsion. When the dosage of emulsifier is increased, the particle size and storage stability are both reduced, creating more stable emulsions, then the trend tends to be stable at last. The particle size and storage stability are both increased as pH value of the system and storage temperature increases. The particle size and storage stability increases firstly and then comes to a plateau with storage time increasing. The gray correlation analysis shows that the correlation between the stability and various influencing factors descends in the order: pH value>storage temperature>emulsifier>asphalt type>storage time， while the correlation between the particle size and various factors decreases in the order: pH value>the storage temperature>emulsifier>storage time>asphalt types.