Abstract: The alkyl substituted derivatives of cyclopentadiene have been synthesized conveniently by the phase transfer catalytic reactions of cyclopentadiene with alkyl halides in the presence of potassium hydroxide and using polyoxyethylene surfactants as catalyst.The reactions were carried out under the solid-liquid two phase systems.The results showed that the ease of the reactions depended upon the reactivity of the alkyl halides.Some alkyl substituted cyclopentadienes were prepared by this method and the polyethylene glycol (PEG)-400 was used as the catalyst.