In this paper， monodispersed CdTe quantum dots are synthesized by soft chemical method. Meanwhile， mercury cadmium telluride （Hg_xCd_1-xTe） quantum dots with the quasi continuous visible to near-infrared spectrum are prepared by ion exchange adjusting the concentration of Hg²⁺. The variable temperature photoluminescence and self-absorption characteristics of near-infrared Hg_0.33Cd_0.67Te quantum dots are deeply analyzed. The results indicate that the fluorescence intensity of Hg_xCd_1-xTe quantum dots decreases linearly with the increase of temperature （0～100 ℃）. The spectral line broad and the peak position has a red-shift （12 nm）. The partial overlap of absorption and emission spectra of quantum dots leads to self-absorption. The increase of self-absorption results in decrease of photoluminescence intensity while the concentration of quantum dots increases.