The invention relates to a power distribution box connecting piece and a power distribution box installation rack provided with the connecting piece. The power distribution box connecting piece comprises a connecting piece body connected with one support upright column of the power distribution box installation rack and the length of the connecting piece body extends in the up-and-down direction. The connecting piece body is provided with a supporting part used for supporting a power distribution box and a connecting part used for being connected with the sidewall of the power distribution box. During the installation of the power distribution box, the power distribution box is placed in an installation space between two support upright columns and can be supported by the supporting part. The connecting part is connected with the sidewall of the power distribution box. In this way, the power distribution box can be stably and reliably fixed onto the installation rack. Meanwhile, the technical problem in the prior art that the power distribution box is complicated in installation process and low in installation efficiency can be solved.