In this letter, a low-complexity suboptimal joint beamforming and power allocation (PA) design scheme for distributed multiple-input multiple-output (D-MIMO) system is proposed. With the objective of maximizing energy efficiency (EE), the developed suboptimal joint scheme can provide closed-form expressions of PA and beamforming. Compared with the existing schemes, the proposed suboptimal joint scheme needs no iterative calculation and yields a lower complexity. Moreover, it can achieve excellent EE quite close to that of the existing algorithms. Simulation results demonstrate the effectiveness and superiority of the proposed joint scheme.