The effect of residence time, catalyst-to-oil (CTO), and temperature of regenerated catalyst (T-RC) on the product distribution of residue fluid catalytic cracking (RFCC) are investigated in a technical pilot scale riser apparatus. Under simulated realistic conditions, thermal cracking predominantly occurs at two different parts of the riser reactor: one is at the bottom of riser for hot catalyst contacting with relatively cool feedstock droplets and another is at the second half of the riser for deactivation of the catalyst. Therefore, the optimal reaction conditions and a modified RFCC process are proposed for lowering thermal cracking and maximizing liquid products. The simulation experiments of the modified process show that product distribution at lower T-RC and higher CTO of the optimal conditions is superior to that of the routine RFCC at a nearly similar conversion level, more than 0.4-2.7 wt % liquid products could be obtained. The balance of hydrogen for the products indicates that the decrease of dry gas and coke at the optimal reaction conditions leads to more H of the feed is distributed into the liquid products.