The invention discloses a method for preparing CdSe and ZnSe quantum dots nanometer particles. Aluminum powder and strong base solution are adopted for the reduction of selenium powder and sulphuric acid is added to generate hydrogen selenide, the hydrogen selenide is brought out by the flow of high purity nitrogen and dissolved in oil amine to obtain oil amine-hydrogen selenide composite; the oilamine-hydrogen selenide composite which is taken as a new selenium precursor, together with cadmium stearate and orzinc stearate, is used for preparing the CdSe and ZnSe quantum dots nanometer particles at high temperature; the prepared quantum dots nanometer particles have controllable spectrum and excellent performance and can be applied to the fields such as biological fluorescence label, optoelectronic materials, etc. Furthermore, the method for preparing quantum dots nanometer particles can avoid the adoption of trioctylphosphineoxide (TOP) which has strong toxicity and high price, and is low in cost and suitable for industrial production.