Belonging to the field of metallurgical sample detection, the invention relates to a preparation method of a standard spectrum sample. The method includes the processes of: component selection, preparation of a standard sample through a continuous casting middle ladle top pouring method, stability investigation and conclusion. The method is characterized in that the process of preparing the standard sample by the continuous casting middle ladle top pouring method comprises the steps of: model baking, sample model establishment, sample model pouring by the top pouring method, demolding, segmentation and surface treatment, physical property detection, surface treatment, chemical component uniformity test, and fixed value analysis. The standard sample prepared in the invention not only satisfies the standard sample requirements in terms of physical property, texture, component range and uniformity, but also has reduced preparation cost and increased sampling number. At least 200 pieces can be prepared every time, thus being over 20 times as many as a model casting sampling number. And the preparation number can satisfy the current production requirements. Thus, the standard sample preparation method of the invention boasts very high practical value.