Abstract: Linear calibration curve is widely used in the field of chemical measurement, but its applicability conditions and uncertainty calculation method need to be further strengthened, and it is unreasonable to rashly use the ordinary least square method when the applicable premise is not met. Based on practical data examples, this paper compares the difference between the ordinary least square method and the weighted least square method. Applying the uncertainty propagation law, the uncertainty calculation formula of the linear calibration curve is derived in detail and compared with the widely used calculation method at present. It is suggested that when determining the calibration curve, whether the uncertainty of the measurement results meets the homogeneity of variance should first be considered, and if it does not, the weighted least square method should be used. When calculating the uncertainty introduced by the calibration curve, the uncertainty of the actual measurement results should be used instead of substituting the residual of the measurement results of the calibration solution.