The present invention discloses a mud shale thermal release water online chromatogram analysis method, which comprises: (1) preparing a standard solution; (2) setting chromatographic conditions; (3) drawing a standard curve; (4) carrying out blank analysis; (5) carrying out sample analysis; and (6) calculating the water content, wherein the water content S in mud shale is calculated according to a formula: S=((y[sample]-y[blank]-b)/a/W). According to the present invention, with the mud shale thermal release water online chromatogram analysis method having the external standard quantitation, the sample consumption is less, the advantages of fastness and accuracy are provided, the problems of too long analysis period or complicated reagent preparing, environment pollution, damage on operator health and the like of other methods are avoided, the water content of the mud shale can be accurately calculated, and the reliable parameters such as the fluid saturation degree and the like can be obtained by combining the mud shale thermal release water online chromatogram analysis method and other testing ways; and the C2-C6 light hydrocarbon contents in the mud shale can be obtained through the external standard quantitation so as to achieve the two purposes through the one method and provide the new convenient and environmentally friendly method for the research of the mud shale.