Abstract: The change of strain rate and stress rate of samples with and without yielding phenomenon was studied during the tensile test under the control of grip separate rate. It is showed that strain rate was different in the different deformation stage,the value of strain rate was much lower than the set value in elastic stage,little higher in yield,and close to the set value in the plastic deformation. And the test rate was enacted in 1-7 mm/min under the testing condition.