The preparation of quantum dot thin films and the accurate determination of optical constants are particularly important in the development and application of their optoelectronic fields. At present, the optical constants of MoTe2 single-crystal films prepared by mechanical exfoliation and chemical vapor deposition are relatively mature. However, the optical constants of 2H-MoTe2 quantum dot films are rarely reported. 2H-MoTe2 quantum dots were prepared by ultrasonic assisted liquid phase exfoliation, and two sizes of 2H-MoTe2 quantum dots were prepared by changing the type of solvent and ultrasonic order. The optical constants such as refractive index, extinction coefficient and dielectric constant of quantum dot films of two sizes were studied by B-spline model and Tauc-Lorentz model using ellipsometry. The results show that the two sizes of 2H-MoTe2 quantum dots have similar refractive index, extinction coefficient and a wider spectral absorption in the visible to near infrared band. And compared with MoTe2 bulk material, it has a lower dielectric constant.