Ti-doping effect on the metal-insulator transition of hollandite vanadate, K 2 V 8 O 16 has been investigated. The transition is accompanied by the charge ordering and the structural change from tetragonal to monoclinic structures with the increase of volume in the low-temperature monoclinic insulator phase. A slight amount of Ti-substitution for V atoms raises the transition temperature up to 270K at x=0.5 in K2V8-xTixO16 from 170K at x=0. This significant rise of transition temperature can be understood as a negative chemical pressure effect caused by the Ti-substitution. On the other hand, the disorder effect from the Ti-substitution makes the transition broad and finally the transition smears out around x=1.0.