Abstract: The optimization of highly selective conversion zone for olefin rich light gasoline in MCP (Maximizing Catalytic Propylene) process was studied and its industrial application at Yangzhou Petrochemical Company was disclosed. The results of industrial application showed that in the selective conversion zone, when adopting the technique of regenerated catalyst met heavy recycle oil (HCO) prior to light gasoline feed in, at a HCO recycle amount of 0.3 t/h, the mass fraction of propylene in LPG could be increased by 2.34 percentage points and the propylene yield could be increased by 0.84 percentage points. The selective located coke on the catalyst formed by the contact of HCO with hot regenerated catalyst could enhance the shape selective function of molecular sieve catalyst, which resulted in converting light gasoline to more propylene.