Abstract: Electromagnetically-induced transparency (EIT) effect emerges in Rydberg atoms under the existence of microwave fields, which makes Rydberg atoms utilizable for detection of weak electric fields. In recent years, a new architecture of radar receiver based on Rydberg atom microwave detection has attracted an extensive attention in the industry. In this paper the external and internal noise sources of the Rydberg atom radar receiver are analyzed, and its sensitivity is estimated. It is pointed out that in the radar detection scenario, the sensitivity of Rydberg atomic receivers which can be prepared at present is less than that of traditional electronic receivers. Several technical improvements for the practicalization of Rydberg atom radar receivers are also proposed in this paper.