Abstract: According to relationship of chemical structure and analgesic activity between 3,5-propanopiperidine analgesics (Ⅰ) and fentanyl, we prepared 1-(β-phenylethyl)-3-methyl-4-methoxy-4-(m-hydroxyphenyl)-3, 5-propanopiperidine (Ⅳ) and a new series of analgesics e. g. N-1-(β-arylethyl)-3-methyl (or hydrogen)-3,5-propanopiperidyl-N-arylpropanamide(Ⅲ) which combined the structures of the two compounds. Pharmacological results showed that most of these compounds are of the same level of potency as morphine.