Three kinds of amides, propionamide, pentanamide and heptamide, were prepared by using propionyl chloride, pentanoyl chloride and heptanoyl chloride as acylating agents reacting with ammounium hydroxide respectively when the temperature was under 10℃. The synthesized amides reacted with acyl chloride which had the same carbon chain length at the temperature of ≤0℃. The products were characterized. The results showed that three kinds of linear-chain dialkylimide possessed symmetrical structure (that were dipropylimide, dipentylimide and dihetylimide) with the melting range from 153.7 to 154.0, 91.5 to 91.7, 89.0 to 89.5℃, and their ultimate yields were 30%, 35% and 33%, respectively. The purity of products obtained could reach over 99%.