The embodiment of the invention provides a method and a device for determining the TOC content and the heterogeneity of source rocks based on well-log and seismic data. The method comprises the steps of obtaining the geology and experimental data of a to-be-measured region; according to the geology and experimental data, obtaining the characteristic curve of the TOC content of hydrocarbon source rocks in the to-be-measured region through forward computation; further obtaining an inversion data volume of the TOC content of hydrocarbon source rocks in the to-be-measured region by utilizing the seismic waveform through reverse computation; respectively determining an isoline plane distribution diagram for the TOC content of hydrocarbon source rocks at the position of a maximum flooding surface during the secular cycle of the to-be-measured region, the position of the maximum flooding surface during the medium-term cycle of the to-be-measured region and the position of the maximum flooding surface during the short cycle of the to-be-measured region by adopting the stratal slicing technique according to the inversion data volume of the TOC content of hydrocarbon source rocks in the sequence stratigraphic framework of the to-be-measured region. According to the technical scheme of the invention, the problem in the prior art that an existing method for determining the TOC content of hydrocarbon source rocks is poor in precision and low in accuracy can be effectively solved. Meanwhile, the technical problem in the prior art that a part of hydrocarbon source rock stratum segment high in TOC content is easily missed is also solved. Therefore, the precision and the accuracy of determining the TOC content of hydrocarbon source rocks are improved.