Objective <p>Placental accreta spectrum (PAS) is a collective term for a range of pregnancy complications caused by abnormal placental implantation, posing a threat to the lives of both the mother and the fetus. This study aimed to screen for placental marker metabolites of PAS and assess the effect of L-Arginine on trophoblast invasion.</p> Methods <p>Placental tissues were collected from a total of 15 pregnant women, including 10 women diagnosed with PAS and 5 women with normal pregnancies. Histological staining was used to characterize pathological changes in the placenta. The changes in endogenous placental metabolites by LC-MS/MS. Subsequently, the role of marker metabolite L-Arginine on HTR-8/Svneo invasion was explored, and protein transcription and expression levels of GPRC6A/PI3K/AKT/MMP2/MMP9 were determined by RT-qPCR and western blot.</p> Results <p>The placentas of PAS patients were mostly infiltrative invasion, with active proliferation and inhibited apoptosis of trophoblast cells. By LC-MS/MS, we identified 13 significantly different metabolites between healthy and PAS pregnant women’s placenta tissue. Among them, placental concentrations of L-Arginine were significantly higher in PAS pregnant women than in controls. In vitro, L-Arginine promoted the proliferation and migration of HTR8/SVneo cells and upregulated the transcription and expression of proteins related to the GPRC6A/PI3K/AKT pathway.</p> Conclusions <p>Our study demonstrates that L-Arginine may promote trophoblast invasion and migration in placental implantation by upregulating the GPRC6A/PI3K/AKT pathway. This provides a new basis for screening appropriate metabolic markers for PAS, thus contributing to the prevention and treatment of PAS.</p>