[ $TiO_2-Nb_2O_5$ ] sol was prepared using sol-gel method. Crystalline properties of gel powder changed from rutile phase to anatase phase with increasing $Nb_2O_5$ additives at $800^{circ}C$, while they retained rutile phase regardless of $Nb_2O_5$ additives at $900^{circ}C,;1,000^{circ}C$. They retained amorphous phase from $50^{circ}C;to;400^{circ}C$, retained anatase phase from $500^{circ}C;to;600^{circ}C$ and had rutile phase over $700^{circ}C$ at 1mole% $Nb_2O_5$ additive. After $TiO_2-Nb_2O_5$ sol retained low viscosity with normal chain structure for a long time, its viscosity increased fast with network structure. DTA properties of gel powder had endothermic reaction due to evaporation of propanol and water about $78^{circ}C$, had exothermic reaction due to propanol combustion about $290^{circ}C$ and had exothermic reaction due to changing of $TiO_2$ phase about $640^{circ}C$.