A method for preparing a quantum dot, a quantum dot, and a display device, are provided. The method includes the following steps: providing a first precursor solution, a second precursor solution, a first selenium precursor solution, and a second selenium precursor solution with a lower reaction activity than the first selenium precursor solution; adding the first selenium precursor solution to the second precursor solution to form an intermediate of the quantum dot; performing the following step at least once to form the quantum dot: adding the first precursor solution and the second selenium precursor solution to the intermediate of the quantum dot and making them react.