The placenta is a dynamic reproductive organ for cattle reproduction and is indispensable for embryonic blood supply, nutrition transportation, and fetal calf development, and it directly affects the development of fetal calf in utero. However, the detailed molecular mechanism of placenta act on fetal calf still remains unclear.In the present study,we used the proteome of placenta to identify the key gene and protein in Low weight(LW) fetal calves and High weight(HW) fetal calves, and reveal the fetal calf growth-related candidate biomarkers by integrative analysis.Placenta proteomics provide new insight into the physiological mechanisms and potential biomarkers for fetal calf development in utero,which can be employed to enhance breeding efficiency and genetic improvement in cattle.