Improved delayed coking process

The invention discloses an improved delayed coking process, aiming at solving the defects of serious heating furnace coking, low liquid product yield and the like in the current delayed coking processes. The process is characterized in that feeds are heated to 360-460 DEG C in a convection chamber or a convection chamber and a radiation chamber of the heating furnace, and then enter a visbreakingreactor for cracking reaction; heavy oil separated from the reaction product enters the radiation chamber of the heating furnace to be heated to 480-515 DEG C and then enters a coke tower; oil gas out of the coke tower singly enters or enters a fractionating tower after being mixed with the gas in the visbreaking reactor for fractionation. By adopting the process of the invention, the delayed coking liquid product yield can be improved, the coke yield reduced, the operation cycle of the delayed coking unit lengthened and the equipment investment lowered at the same time.