完整的句子应该是这样的：

Win-win cooperation is the only choice for us, be it in good times or bad.

【翻译】无论是顺境还是逆境，合作共赢是我们唯一的选择。

be it in good times or bad，是“让步状语从句”的特殊说法。等于：

whether it is in good times or bad

whether it may be in good times or bad

whether it be in good times or bad