The invention provides a method for manually building oil shale underground broken bodies and relates to the technical field of oil shale underground in-situ transformation. The method comprises the following steps: drilling a horizontal well; after drilling the horizontal well, performing staged fracturing on the horizontal well by a hydraulic fracturing method; after fracturing, injecting a liquid explosive into the horizontal well, enabling the liquid explosive to enter a stratum fracture formed by staged fracturing, and further reinforcing the underground oil shale layer by using the energy generated by explosion to generate the broken body; enhancing the porosity and the permeability of the oil shale exploiting layer to form an underground in-situ transformation broken body; and drilling a plurality of vertical wells, wherein the oil shale layer between the horizontal well and the vertical wells generates sufficient heat transfer area at the moment. By the method, the cost is reduced, the rubblization of the oil shale layer can be improved, the effect is better as compared with that of the conventional fracturing method, the heat-conducting capability of the oil shale stratum can be improved obviously, development of an oil shale in-situ process is benefited, and conditions are provided for realizing commercial use of the oil shale.