As the earliest artificial building materials, burnt clay products led to a fundamental improvement in the living environment of prehistoric human beings. There are many viewpoints on the causes of burnt clay buildings, such as artificial baking, accidental fire, and abandonment customs, etc. Determination of the firing temperatures of burnt clay materials in prehistoric architectural relics is helpful by providing important information on technical development and enriching research on the history of prehistoric buildings.  Magnetic research shows that soil and other sediments at archaeological sites contain newly-formed magnetite, maghemite and other strongly magnetic minerals after being heated, resulting in significant enhancement of magnetism, and that the mineral compositions and magnetism hardly change thereafter.However, when the re-firing temperature is close to or greater than the original firing temperature, the destruction of original minerals or the formation of new minerals in samples causes a change in mineral magnetism. As a result, analysis in the laboratory of the characteristics of magnetic susceptibility variation of heated clay with temperature changes can reflect the firing temperatures of burnt clay products. Sujiacun site is an important settlement site from the late Dawenkou culture to the early middle Longshan culture. The fifth layer is a burnt clay layer with a thickness of about 20—40 cm that covers the whole site. It is speculated that the layer is a construction waste accumulation site or a man-made accumulation site caused by house collapse. In this study, the compositions, structural characteristics and firing temperatures of burned clay samples unearthed from Sujiacun site were analyzed by X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF) and magnetic susceptibility method. The results show that the white clay (kaolin) raw material was artificially added to the white ash layer of the burnt clay samples from the Sujiacun site, and that plant debris was intentionally added as an extender to the burnt clay layer. It is speculated that this is straw-reinforced mud used to improve the strength and adhesion of the body. This verifies the speculation that the samples may come from building materials. The burnt clay samples were artificially fired, with the firing temperatures ranging from 600 ℃ to 700 ℃. There is no vitrification inside the burnt clay, the structure is loose and the compressive strength is low. When formulating a scheme for protection of burnt clay relics, we should take targeted protection measures according to the firing temperatures of burnt clay in order to achieve the best protection effect. The appearance of burnt clay products brought humans into a new level of skill in building houses. The study of burnt clay products is of great significance to understanding the architectural technology of the late Neolithic Age in Shandong Province. The magnetic susceptibility method is suitable for studying the firing temperatures of low-temperature-fired burnt clay samples and could be further applied to the study of the firing temperatures of early pottery (especially low-temperature pottery).