We　have　prepared　GexSe10Te90-x　glasses　with　a　composition　of　x　from　17.5　to　26.25　and　measured　their　properties　using　various　diagnosis　tools.　It　was　found　that,　all　the　glasses　have　a　transmittance　more　than　40%　at　a　wavelength　range　from　2　to　15　mu　m,　and　linear　refractive　index　n0　decreases　but　optical　bandgap　energy　Eg　increases　with　decreasing　Te　contents　in　the　glasses.　We　also　analysed　the　evolution　of　n2　and　beta　as　a　function　of　Ge　content,　both　the　evolution　of　n2　and　beta　are　close　to　the　prediction　by　Sheik-Bahae　et　al.　for　optical　nonlinearity　of　semiconductors.　In　all　cases,　the　nonlinear　optical　refractive　index　n2　measured　at　3.0　mu　m　is　larger　than　that　at　2.5　mu　m　due　to　the　two-photon　resonance　effect,　and　a　maximum　nonlinear　index　is　2.46　x　10-13　cm2/W　at　composition　of　Ge17.5Se10Te72.5.　Such　larger　nonlinearity　around　10-13　cm2/W　observed　in　the　present　paper　is　one　order　of　the　magnitude　larger　than　that　in　S-　and　Se-based　chalcogenide　glasses,　demonstrating　potentials　of　Te-based　glasses　for　the　applications　as　mid-　and　far-infrared　nonlinear　optical　devices.