The fluid catalytic cracking (FCC) performances of three typical coker gas oil (CGO) in China were investigated in a fixed fluidized-bed reactor. Effects of the blending ratio of CGO to vacuum gas oil (VGO), comparative FCC performances of different CGOs, and effects of operating conditions on CGO catalytic cracking performance were discussed. Based on these, the competitive adsorption effects on CGO catalytic cracking were analyzed. The results show that the conversion decreases with the increasing blending ratio of CGO to VGO due to lower reactivity of coker gas oils. The catalyst to oil ratio (CTO) has a larger influence on CGO catalytic cracking performance than the reaction temperature and weight hourly space velocity (WHSV) has. A competitive reaction area and a free reaction area can be distinguished based on the relation of CTO and CGO catalytic cracking performance. (C) 2013 Elsevier B.V. All rights reserved.