由于您想要_
充当明确的连字点,您可以告诉 TeX 它是什么:

\documentclass{article}
\usepackage{array}
\usepackage[T1]{fontenc}
\begin{document}
\begin{tabular}{l>{\raggedright\arraybackslash\catcode`\_12 \hyphenchar\font`\_}p{2cm}}
aaa & ABCD_243_SSD_FCA_SDD\\
bbb & ZZZ_1234_THIS_THAT_THING\\
\end{tabular}
\end{document}