The invention discloses a method for measuring purity values and uncertainty degrees of standard substances of phenol and hydroquinone. The method comprises the following steps: screening raw materials for purity qualification; performing qualitative confirmation on to-be-measured samples by combining a gas chromatography-mass spectrometry with a Fourier transform infrared spectroscopy; measuring the purity of the to-be-measured samples by combining three methods different in principle including a GC method, an HPLC method and a DSC method; sub-packaging the to-be-measured samples; checking uniformity and stability; calculating to obtain the uncertainty degree caused by purity measurement; calculating the uncertainty degree caused by the uniformity and the stability according to step four; and synthesizing all the uncertainty degrees to obtain a total uncertainty degree. The method provided by the invention has accurate qualification, reduces system error, adopts a strict statistical data processing method and a comprehensive uncertainty degree evaluation method, ensures accuracy, stability and traceability of measured values, and obtains high-purity standard substances of phenol and hydroquinone.