During the deeply diesel oil desulfurizing and dearomatizing process, raw material oil and hydrogen are mixed and contacted with hydroupgrading catalyst, hydrocracking catalyst or hydrofining catalyst in the first reactor; the reaction effluent is stripped at high temperature and high pressure in a hydrogen stripping tower and contacted with conventional hydrofining catalyst in the second reactor; the effluent from the second reactor is passed through high pressure separator, low pressure separator and fractionating tower successively; the reaction product is divided into naphtha and diesel oil fraction in the fractionating tower; the hydrogen-rich gas separated from the high pressure separator and the stripping tower is mixed with fresh hydrogen and the mixed gas is separated into two parts to the first reactor and the second reactor separately.