The creep tests were carried out on commercial purity zirconium (CP-Zr) in different states under the stresses of 0.9R_p0.2、0.925R_p0.2、0.95R_p0.2、0.975R_p0.2 at ambient temperature (AT). Steady state creep rate and creep stress were calculated. The microstrutures of CP-Zr before and after annealing and creep tests were analysied. The results indicate that the threshold stress of CP-Zr in different states exists in creep tests at AT. When the creep stress is greater than the threshold stress value, the density of dislocation of CP-Zr obviously increases with the creep stress increasing, the significant dislocation pile-up can be observed at grain boundaries. It is found that the UFG CP-Zr after annealing at 250°C can not only maintain grain size and stable microstructure, but also keep the original high strength and improve the plasticity compared with CG CP-Zr. In addition, the annealing treatment at 250°C can improve the creep properties of UFG CP Zr, weaken the creep stress sensitivity and enhance the creep resistance.