A new series of poly(bisbenzothiazole)s containing bulky pendant cyclohexylidene or 4-tert-butylcyclohexylidene group was synthesized. Their structures were characterized by NMR (H-1, C-13), FTIR, and EA. These polymers exhibited good solubility, thermal stability, and an amorphous nature. The photophysical properties of them were investigated in detail by UV absorption spectroscopy and photoluminescence spectroscopy. Compared with poly(p-phenylene benzobisthiazole), the absorption maxima of these polymers were all blue shifted, and their optical bandgaps were increased. The emission peaks, having different intensity, were also blue shifted. They both changed in shape and position gradually with the increasing concentration, which showed the evidence of aggregate formation. In addition, the degree of aggregation was decreased with the increasing size of bulky pendant group and the PL quantum yield could be improved by the introduction of bulky pendant group. The result of electron paramagnetic resonance studies showed the intrinsic paramagnetic defects in this class of polymers. A new soliton-antisoliton model was constructed to interpret these intrinsic paramagnetic signals.