Over the past decades, considerable progresses have been achieved in the research of biosynthesis of ODAP (β-N-oxalyl-L-α,β-diaminopropionic) in grass pea (Lathyrus sativus L.). The progresses include the separation, identification and verification of the precursors and the biosynthesis procedure of ODAP. The corresponding genes which guide the biosynthesis of ODAP have not yet been cloned so far, mainly because its synthetase could not be separated and characterized. Therefore the biosynthesis of ODAP can not be blocked by the antisense RNA technology. In our previous work, the ODAP precursors were successfully controlled as to reduce the ODAP accumulation with the application of the corresponding inhibitors in grass pea. ODAP content was found to be closely related to plant stress resistance, for the reason that ODAP can effectively remove -OH in grass pea leaves. The same effects were observed from the experiment of exogenous ODAP application. ODAP, as a nitrogen compound as well as one of highly soluble amino acids, acts in a similar way to proline and polyamine under the adverse stress. It is so easy to be dissolved in water that it can be accumulated rapidly in large quantities. In this case, it can be argued that ODAP may act as a cellular osmotic regulator and an anti-dehydrator, and must play an important role in the nitrogen and energy metabolism. In addition, a few potential approaches for the future research have been suggested here.