Abstract: Provided are a T cell deleting the Ryr2 gene and a preparation method. Also provided are an Ryr2 antagonist, an Ryr2 overexpressing T cell, a method and applications for regulating Ryr2 expression, regulating basal Ca2+ oscillation, regulating m-Calpain activity, and increasing bonding strength between T cells and DC cells, applications of a reagent implementing the functions in preparing a medicament for treating an infectious disease, inflammation, or tumor, and a method for transforming Tconv cells into being functionally similar to Treg cells.