The embodiments disclosed herein provide a peptoid, which is a compound of Formula I or a stereoisomer, a mixture of stereoisomers, or a pharmaceutically acceptable salt thereof. N—R4, N—R3, N—R2, and N—R1 in Formula I are respectively. The peptoid has a strong binding ability with EGFR protein. It can be used not only for targeted treatment of diseases associated with EGFR protein, but also for imaging detection or prognosis monitoring of diseases associated with EGFR protein.