Evaluating the uncertainty of the result of a measurement of a physical quantity is very effective to the improvement of the measurement technique. The new expression of uncertainty in measurements has been established to standardize the expression of error evaluation on measurement results. In this text, the sources of uncertainty on thermal expansion measurement techniques by using a pushrod dilatometer and a laser interferometric dilatometer were classified and the uncertainty of the result in the linear thermal expansivity measurements was presented according to the guide of the expression of uncertainty.