Electrical treeing characteristics of hybrid materials made from titanium alkoxide Ti(OCH2CH(C2H5)C4H9)(4) and alkoxysilane-terminated polydimethylsiloxane (PDMS) in different TA/PDMS ratio was investigated. The development of AC tree of sample was mounted on a glass substrate with needle electrode was observed by CCD camera and computer. The tree inception voltage increased and tree growth speed decreased with increase in TA/PDMS ratio of the hybrid. It is suggested that the variation of crosslinking density and homogeneity of dispersion of silica clusters influenced on their tree propagation characteristic. We found that the hybrid made from the alkoxysilane-terminated PDMS and TA has good electrical insulating property compared with conventional PDMS-based hybrid materials and silicone rubber.