Abstract: Naphthalene asphalt was synthesized at 160-240℃ using naphthalene as a raw material and AlCl₃ as a catalyst, and its de-ashing by ultrasonic treatment, stirring, heating, and acid and/or alkali washing was investigated. Results indicated that naphthalene-based mesophase asphalt with an ash content less than 500 ppm could be prepared by twice washing in an alkali followed by acid washing for 4 times and finally water washing for 10 times at 80-90℃ under ultrasonic or stirring conditions.