Abstract: Based on the viscoelastic theory, Euler-Bernoulli beam theory and piezoelectric theory, a static pull-in model and governing equations of piezoelectric viscoelastic microbeams in thermal-electric couple field are developed considering the creep phenomenon of the structure. The pull-in critical conditions of piezoelectric viscoelastic microbeams are studied and the influence of piezoelectric voltage and temperature on the pull-in behaviour is discussed. The results show that the lasting pull-in voltage can be used as the critical condition of the static pull-in instability; the temperature and the control voltage of piezoelectric layers have influence on the critical condition value of static pull-in instability. This paper offers theoretical reference to the design and optimization of beam-type MEMS.