Abstract: Basic steps of Continuous Propagation Model of Uncertainty are as follows:firstly, evaluate the uncertainty of standard series and obtain the standard uncertainty;secondly,determine the response value of standard series time again and calculate the mean and standard uncertainty; thirdly, fit the standard curve by double errors regression and obtain the double-errors fitting equation along with calculation equation of standard uncertainty;and then calculate the different values between standard points and calibration points,moreover, convert it into the standard uncertainty;finally, total uncertainty of all above are calculated by the rule of uncertainty propagation. The 1, 2, 4 steps are calculated by interpolation in actual measurement. Furthermore ,calculation results by different fitting methods are compared and proved the measurement uncertainty that calculated by the model is more reasonable.