The invention relates to a rod cluster critical heat flux density test device which comprises a pressure-bearing shell, a flow passage, a heating rod cluster and a conductive mounting board on which the rod cluster can be fixedly mounted, wherein an outlet and an inlet, through which a working fluid can enter and exit, are formed in two ends of the pressure-bearing shell respectively, and are communicated with the inner chamber of the pressure-bearing shell; the flow passage is arranged in the pressure-bearing shell axially, while two ends of the flow passage are communicated with the outlet and the inlet respectively; the mounting board is matched with the end surface, corresponding to the outlet, of the pressure-bearing shell separably, so that the heating rod cluster on the mounting board can penetrate the flow passage; the mounting board is electrically connected with the heating rod cluster, and insulated from the pressure-bearing shell. Being insulated from the pressure-bearing shell, the mounting board can be electrically connected with the heating rod cluster after the mounting of the heating rod cluster; the heating rod cluster is connected with a power source through the mounting board, so that the mounting of the heating rod cluster is simplified, and the insulation effect between the main body part of the test device and the power source can be guaranteed.