A quantum dot preparation method, comprising: providing a first quantum dot core growth reaction system to perform a first quantum dot core growth, precursors in the first quantum dot core growth reaction system including metal element precursors and non-metal element precursors, the metal element precursors including at least a metal element M 1 precursor, and the metal element in the first quantum dot core including at least the metal element M 1; adding a precursor of a metal element M 2 to the first quantum dot core growth reaction system during the growth process of the first quantum dot core; and interrupting the growth of the first quantum dot core to make the metal element M 2 and the metal element M 1 in the first quantum dot core exchange cations to perform a second quantum dot core growth, wherein the precursors in the first quantum dot core growth reaction system is the metal element M 1 precursor and a non-metal element X 1 precursor, and composition of the first quantum dot core is M 1 X 1, further comprising: adding the precursor of the metal element M 2 to the first quantum dot core growth reaction system during the growth process of the first quantum dot core; and interrupting the growth of the first quantum dot core to make the metal element M 2 and the metal element M 1 in the first quantum dot core exchange cations to perform the second quantum dot core growth, composition of the second quantum dot core M 1 M 2 X 1 is GaInP or InGaP. providing a first quantum dot core growth reaction system to perform a first quantum dot core growth, precursors in the first quantum dot core growth reaction system including metal element precursors and non-metal element precursors, the metal element precursors including at least a metal element M 1 precursor, and the metal element in the first quantum dot core including at least the metal element M 1; adding a precursor of a metal element M 2 to the first quantum dot core growth reaction system during the growth process of the first quantum dot core; and interrupting the growth of the first quantum dot core to make the metal element M 2 and the metal element M 1 in the first quantum dot core exchange cations to perform a second quantum dot core growth, wherein the precursors in the first quantum dot core growth reaction system is the metal element M 1 precursor and a non-metal element X 1 precursor, and composition of the first quantum dot core is M 1 X 1, further comprising: adding the precursor of the metal element M 2 to the first quantum dot core growth reaction system during the growth process of the first quantum dot core; and interrupting the growth of the first quantum dot core to make the metal element M 2 and the metal element M 1 in the first quantum dot core exchange cations to perform the second quantum dot core growth, composition of the second quantum dot core M 1 M 2 X 1 is GaInP or InGaP. adding the precursor of the metal element M 2 to the first quantum dot core growth reaction system during the growth process of the first quantum dot core; and interrupting the growth of the first quantum dot core to make the metal element M 2 and the metal element M 1 in the first quantum dot core exchange cations to perform the second quantum dot core growth, composition of the second quantum dot core M 1 M 2 X 1 is GaInP or InGaP.