The utility model provides a supporting anchor cable for a bottom plate of a roadway. The supporting anchor cable for the bottom plate of the roadway comprises a columnar hollow grouting anchor cable body, wherein the hollow grouting anchor cable body is provided with a through grouting pipe, a grouting adapter is arranged at one end of the hollow grouting anchor cable body, the hollow grouting anchor cable body is sleeved with a sleeve, the sleeve is shorter than the hollow grouting anchor cable body, the distance between the sleeve and the first end of the hollow grouting anchor cable body is smaller than the distance between the sleeve and the second end of the hollow grouting anchor cable body, the portion, close to the second end of the hollow grouting anchor cable body, of the sleeve and the hollow grouting anchor cable body are fixed together in a sealed mode, multiple grout outlets are formed in the portion, between the second end of the hollow grouting anchor cable body and the sleeve, of the hollow grouting anchor cable body, and the grout outlets are communicated with the grouting pipe. According to the supporting anchor cable for the bottom plate of the roadway, high prestressing force can be borne in a wide range, and the self-bearing capacity of the bottom plate of the roadway is improved.