n present paper the aromatic-aliphatic copolyamides with different sequencestructure were synthesize from tefrphthalyl chloride (TPC)

p-phenylenediamine (PPD ) and aliphatic diamine (ADA

H2N - (CH2)n -NH2

n=2

6 ). The relationship between sequence structure of copolyamides

includingrandom degree (B) and number average sequence length (Ln)

and the lyotropicliquid crystalline properties

including critical concentration (C*) and the type ofmesogenic phase was studied. The results show that the critical concentration of the liquid crystalline copolyamides increses with the raise of B and decress of Ln and the mesogenic phases of copoly amides transform from nematic to smectic as the LnA/LnP is approximately equal to 0.20.