Abstract. The conjugated polymers TEB1 and TEB2 were synthesized by Wittig and Wittig-Horner reaction, and the conjugated polymer nanoparticles CPNs1 and CPNs2 were prepared by reprecipitation method with TEB1 and TEB2, respectively. Moreover, the morphology and fluorescence of CPNs were investigated. The synthetic results indicated that the average molecular weight was improved effectively by Wittig-Horner reaction. CPNs2 with a higher average molecular weight showed a better feature and bright fluorescence.