Abstract: The unsupported Ru-Zn-B catalysts were prepared by chemical reduction method for selective hydrogenation of benzene to cyclohexene.The influence of preparation conditions such as zinc content,dropping sequences and pH value of washing solution etc.on performance of the Ru-Zn-B catalyst was investigated in detail .It was concluded that under the condition that the amount of zinc was about 10%,by reversed dropping sequence adopted and the precipitate washed thoroughly to pH=7.5 with distilled water,the best s...