The transgenic wheatgrasses were investigated in the case of a hybrid wheatgrass (A. cristatum х A. desertorum cv. ‘Hycrest-Mengnong’). Based on the established regeneration system, the p5CS gene, which regulates the last step of proline synthesis in plant, was transformed into wheatgrass with phosphinothricin acetyltransferase (bar) conferring herbicide resistance as selecting gene. The transformation was conducted through microprojectile bombardment of callus derived from immature inflorescence by co-transformation. The obtained transgenic plants can provide the new germplasm resource for wheatgrass genetically improvement.The results of PCR and Southen analysis displayed that the exogenous p5CS gene had integrated into the genome of transgenic wheatgrass.The assay of RT-PCR showed the transgenic p5CS had expressed at transcript level.The transgenic frequencies of p5CS gene were 0.11%.