Three phosphorus-nitrogen DOPO type flame retardants for epoxy resin were synthesized through two steps from p-phenylenediamine, 4-fluorobenzaldehyde, 4-nitrobenzaldehyde, 4-methoxybenzaldehyde and 9,10-dihydro-9-oxa-10-phosphoryl phenanthrene-10-oxide (DOPO). The intermediates and the target compounds were characterized by 1H NMR and FTIR. The obtained retardant and 4,4'-methylenedianiline were added to EP and transparent cured epoxy resin were obtained. The flame retardant performance of the cured products was investigated, respectively. The results indicated that with the increase of phosphorus content in the cured products, their flame-retardant performance increase. When the phosphorus content reached 1.00 w%, the cured EP can meet UL 94 V-0 class. The limiting oxygen index of BNP-DOPOD/DDM/EP was determined to be 37.0 as the highest among them.