The invention relates to a composition and a method conducive to acquiring follicular regulatory T cells in vitro and an application of the composition. The invention proves that differentiation and number proliferation of in-vitro Tfr (follicular regulatory T cells) can be effectively induced by the aid of irritation of TGF (transforming growth factor)-beta, IL (interleukin)-2, anti-CD3 antibodies, anti-CD28 antibodies and baicalin, and expression of Foxp3 in the Tfr is facilitated. The Tfr cells amplified by the method can be used for treating autoimmune diseases and chronic inflammatory diseases, the autoimmune diseases include lupus erythematosus, dermatomyositis, vasculitides, sicca syndrome, scleroderma, rheumatoid arthritis, ankylosing spondylitis, disseminated sclerosis and autoimmune hepatitis, and the chronic inflammatory diseases include diabetes, coronary heart diseases, hyperlipemia, eczema, vitiligos, atopic dermatitis, lichen planus and the like.