With the development of wireless network and electronic technologies,the wireless sensor network (WSN) has been widely used in many applications.One of the most important applications is wireless medical sensor network (WMSN),which makes modern health-care more popular.However,most of the sensor data transmitted in the WMSN is patient-related information.The sensor data are important and should be confidential.In addition,the attackers may also maliciously modify these sensor data.Therefore,both security and privacy are two very important issues in WMSN.A user authentication protocol and data security transmission mechanism based on bilinear pairing is proposed to protect data security and privacy.The proposed protocol enables the medical staff to monitor the health status of health care workers and provide timely and comprehensive health care information to the patient.Finally,through security and performance analysis,it can be found that the proposed authentication and key agreement protocol can resist common attacks such as impersonation attack,replay attack,online or offline password guessing attack,and stolen verifier attack.At the same time,this agreement is also in line with the performance of WMSN application environment.