Abstract: The effect of reaction temperature, catalyst/oil ratio, WHSV, and water/oil mass ratio on product distribution, light olefins and light aromatics yields was investigated using pipeline VGO as a feedstock. The best process parameters are: 560 ℃, ratio of catalyst to oil (C/O) of 6, WHSV of 2h-1 and water to oil (W/O) of 10. Daqing VGO and intermediated pipeline VGO were employed as cracking feedstocks to examine how feedstock properties impact on the yields of light olefins and light aromatics under the same conditions. The results indicate that the paraffin based feedstock is better in maximizing yields of light olefins and light aromatics, even more light aromatics can be produced at larger catalyst/oil ratio. Using paraffin base VGO, more light olefins and aromatics can be obtained simultaneously. The pathway of light aromatics formation was investigated. It is discovered that most light aromatics are formed by breaking side chain of the mononuclear aromatics when the conversion is low, while the light aromatics from dehydrocyclization of olefins becomes gradually the main pathway when the conversion is higher.