5-o-tolyl -2-pentene(OTP) was prepared by o-xylene and 1,3-butadiene under sodium as catalyst and potassium carbonate as dispersing agent .The effects of catalyst dosage, mass ratio of dispersing agent to catalyst, reaction temperature, reaction time and molar ratio of o-xylene to 1,3-butadiene were investigated. The best technical parameters were obtained : the molar ratio of o-xylene to 1,3-butadiene is 5∶1, reaction temperature is 175 ℃, reaction time is 2.5 h, mass fraction of catalyst is 0.25％, mass ratio of dispersing agent to catalyst is 16∶1.The yield of OTP is 71.2％ under the best technologic conditions. The technology has a series of advantages, for example, the process is simple, the reaction time is short, what's more, it's easy to achieve industrialization open up.