The invention discloses a 
wireless body area network symmetric key negotiation method. A promise is initiated to a node B by a node A. The 
wireless body area network symmetric key negotiation method is characterized by comprising the steps that: the node A acquires a physiological 
signal at a tp moment, the physiological 
signal is set as w; then a sharing secret key is generated according to the w, data is transmitted to the node B in a hidden manner; the node B extracts a physiological 
signal at the same moment, the physiological signal is denoised and the value of the physiological signal is verified whether to be correct; if the value of the physiological signal is correct, a negotiation secret key is solved; and if the value of the physiological signal is wrong, the physiological signal is obtained near the moment w, and the secret key is continuously solved. According to the 
wireless body area network symmetric key negotiation method, the requirement of accurate synchronization for time is avoided, the problem of 
high energy consumption of frequent 
broadcasting of synchronous signals is solved; and in a process of secret key negotiation, most of nodes are used for 
processing data without transmitting the data, thus the 
energy consumption in the process of secret key negotiation is effectively reduced. According to the wireless 
body area network symmetric key negotiation method, the negotiation is unconcerned with the entropy of the signal, a weak 
time synchronization method and a secret key presetting technology are adopted, and a better 
attack preventing property is achieved.