The synthesis of pentacyclo [5.4.0.02,6.03,10.05,9] undecane (PCUD) was accomplished by cyclopentadiene and phenylhydrazine as raw materials through Diels-Alder addition reaction, [2 2] cycloaddition reaction, the Huang Minlon Reduction. During the Huang Minlon Reduction, toluene and diethylene glycol as mixed reaction solvents, the effect of reaction temperature (T2) and reaction time (t2) on the reduction yield was investigated by one-pot reaction on the basis of single-factor tests. The optimum conditions were as follows: n(pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione):n(potassium hydroxide):n(hydrazine)=1:7.5:14, the reaction being conducted at 120 ℃ for 3 h, followed by react- ion at 180 ?C for 4 h. The reduction yield could reach 76.2%. Subsequently, using the volatile characteristics of PCUD, the recycling of diethylene glycol and potassium hydroxide was investigated in the synthesis process of Huang Minlon Reduction, the average yield of PCUD reached 75.2% in 11 times of recycle that had been carried out.