Inspired by the mechanism of behaviour control of organisms, this paper attempts to build an underlying model of their physical and psychological activities in a dynamic environment with the purpose to achieve the self-adaption of robot behaviour in a complex, changeable environment. It designs an internal environment and emotion- & motive-generating models based upon the endocrine regulation mechanism (ERM). The robot relies upon the dynamic stability of the internal environment to accomplish its self-adaption to the external environment. The emotion-generating model is applied to in vivo and in vitro contingencies of various kinds; by releasing hormones, the emotion generated influences the robot’s in vivo and in vitro perception, and then its behavioural choice. The motive-generating model is employed to maintain the relative stability of the internal environment, and the motive generated leads to the corresponding behavioural choice directly. The experimental results prove the effectiveness of this ERM-based self-adaptive robot model.