hi£¬all
 my question as title described£¬Now I used the following method:

\starttext
\placetable[here][tab:multilinesinonecell]{Multi Lines in
  One Cell}
\starttable[|c|c|c|][textwidth=8.8cm]
\HL
\NC \JustLeft FIRST COL \NC  \JustCenter \bf SECOND COL \NC\SR\HL
\NC \JustLeft first line      \NC  \JustLeft  one line in cell \NC\MR
\HL
\NC \JustLeft second line \NC  \JustLeft first line in second line's 2nd
col \NC\MR
\NC                                \NC \JustLeft second line in second
line's 2nd col \NC\MR
\HL
\NC \JustLeft third line     \NC \JustLeft third line's 2nd col \NC\LR
\HL
\stoptable
\stoptext

Thanks in advance!

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PengCZ