The creep tests were carried out on Ultra-fine grained commercial purity zirconium under the stresses of 0.875 Rp0.2、0.9 Rp0.2、0.9125 Rp0.2、0.925 Rp0.2、0.9375 Rp0.2、0.95 Rp0.2 at ambient temperature. Steady state creep rate was calculated. The creep fracture of UFG CP Zr was investigated by SEM. A new expression was proposed which fit the creep of UFG CP Zr better. It was found that the creep saturation phenomenon happened under 0.875 Rp0.2; the steady state creep rate increased with the rise of creep stress which led the steady state creep stage shortening; the maximum of steady state creep rate was 3.140×10-6s-1 under 0.95 Rp0.2. According to the calculated creep stress exponent, the creep mechanism can be categorized into the dislocation motion. The creep fracture of UFG CP Zrwas ductile fracture.