In order to obtain polymers having high second order nonlinear optical susceptibility, a series of novel polymers that contain a diacetylene group, in the main chains and a polar chromophore (Disperse Red 19) were synthesized and characterized. These poly(hexa-2,4-diynylene-1,6-dioxydicinnamates) undergo crystallization it, dimethylformamide solution, and the polymer crystals were only soluble in N-methylpyrrolidinone. The polymer films could be cross-linked. by irradiation of UV light to give completely insoluble materials. Preliminary experiments on second order nonlinear properties of these polymers showed that the para-polymer, was found to have nonlinear optical coefficients about five times greater than the meta-polymer.