A catalytic conversion process which comprises catalytic cracking reaction of a hydrocarbon feedstock contacting with a medium pore size zeolite enriched catalyst in a reactor, characterized in that reaction temperature, weight hourly space velocity and catalyst/ feedstock ratio by weight are sufficient to achieve a yield of fluid catalytic cracking gas oil between 12% and 60% by weight of said feedstock, wherein said weight hourly space velocity is between 25h -1 and 100 h -1 , said reaction temperature is between 450°C and 600°C, and said catalyst/feedstock ratio by weight is between 1 and 30. This invention relates to a catalytic conversion process, especially for heavy feedstock oil to produce higher octane gasoline and an enhanced yield of propylene. More particularly, the invention relates to a process to utilize petroleum oil resources efficiently for decreasing the yield of dry gas and coke significantly.