For long time it lasted of evaluation and screening of germplasm resources from different Lathyrus cultivars to get novel lines with low βNoxalylLα, βdiaminopropionicacid (βODAP) content or protease inhibitor activities. To investigate the possible relationship between βODAP content and protease inhibitor activities, we conducted several tests including sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDSPAGE), enzymatic measurement, correlation analysis etc. referring to six cultivars with two closely related species L. sativus and L. cicera included. The results suggested that: (1) SDSPAGE analysis of seed globulins and prolamins revealed significant difference in their protein profiles. (2) Kunitz trypsin inhibitor (KTi) activity in different Lathyrus cultivars ranged between 100 and 190 trypsin inhibitor unit, while BowmanBirk inhibitor (BBi) activity ranged between 5 and 9 chymotrypsin inhibitor unit. (3) The Pearsons correlation coefficient up to 0.76 suggested a significant positive correlation between βODAP content and serine acetyltransferase activity. (4) Correlation analysis of βODAP biosynthesis related genes and BBi genes expression from transcriptomic database (SRP145030) suggested a significant negative correlation between them. These results will help to further investigate the regulation of βODAP and BBi biosynthesis and improve sulfur amino acid content in Lathyrus cultivars.