默认的大括号（pgfmanual.pdf-p355）

\documentclass[tikz,border=0pt,10pt]{standalone}\usetikzlibrary{decorations.pathreplacing}\begin{document}\begin{tikzpicture}\node (a) {A};\node (b) at (2,1) {B};\draw (a) -- (b);\draw[decorate,decoration=brace] (a) -- (b);\draw[decorate,decoration={brace,mirror},red] (a) -- (b);\draw[decorate,decoration={brace,mirror,raise=5pt},blue] (a) -- (b);\end{tikzpicture}\end{document}

修改后的大括号

\documentclass[tikz,border=0pt,10pt]{standalone}\usepackage{expl3}\ExplSyntaxOn\int_zero_new:N \g__prg_map_int \ExplSyntaxOff\usetikzlibrary{decorations.pathreplacing,calligraphy}\begin{document}\begin{tikzpicture}\draw[decorate,decoration={calligraphic brace,amplitude=4mm},ultra thick] (0,0) -- (8,0);\draw[decorate,decoration={calligraphic brace,amplitude=2mm},ultra thick] (0,1ç) -- (8,1);\draw[decorate,decoration={calligraphic brace,amplitude=6mm},ultra thick] (0,2) -- (8,2);\end{tikzpicture}\end{document}