A series of NiO/SiO2 aerogel catalysts were prepared by sol gel method. The effects of the nickel content on the structure and existing forms of NiO/SiO2 aerogel catalysts were investigated by using XRD, TPR and FT IR. The results showed that there were interactions between NiO and SiO2. But as nickel content increased, the interaction decreased. The nickel oxide in the catalysts appeared in different forms as nickel content was changed. When the content was less than 13%, Ni? entered into the SiO2 structure completely and it became clusters after calcining. If the content altered from 20% to 50%, NiO existed as both microcrystal and clusters, the later spices was dominating. However, when the content increased to 70%, microcrystal became the primary components. The series of NiO / SiO2 aerogel catalysts were prepared by sol gel method. The effects of the nickel content on the structure and existing forms of NiO / SiO2 aerogel catalysts were investigated by using XRD, TPR and FT IR. The results showed that there were Nickel in the compounds was less than 13%, Ni? entered into SiO2 content completely, and the interaction decreased it became clusters after calcining. If the content altered from 20% to 50%, NiO existed as both microcrystal and clusters, the later spices was dominating. However, when the content increased to 70%, microcrystal became the primary components.