For the first time, a series of second-order NLO poly(arylene-ethynylene)s, in which an isolation chromophore was introduced to enhance the NLO coefficients, were successfully designed and synthesized. Thanks to the isolation chromophore, these polymers demonstrated good NLO activities and optical transparency. To further improve the comprehensive performance of the polymers, different isolation groups of various sizes were introduced to subtly modify the structure of the polymers according to the “suitable isolation group” concept. The naphthalene (Np) group was found to be a “suitable isolation group” in this series of polymers and polymer demonstrated the highest d33 value (122.1 pm V−1) of these five polymers. Interestingly, polymer , which contained a pentafluorophenyl ring as an isolation group, exhibited a much higher NLO effect and stability than polymer , which just contained normal phenyl rings as isolation groups (97.2 versus 62.5 pm V−1), thus indicating the advantages of the ArArF self-assembly effect in the field of non-linear optics.