The need to reduce energy consumption for lowering operating costs has pushed energy efficiency to become one of the major issues of current research in the field of ad hoc networks. In this paper, a new cooperative strategy of multipleinput- multiple-output (MIMO) based on spatial modulation (SM) for the randomly distributed nodes (CMIMO-SMR) in an ad hoc network is proposed to optimize the whole energy consumption of the network. In this new strategy, the head node and the assistant node are jointly set up using a cooperative technique in each cluster to obtain the diversity. In this strategy, the effect of the amount of nodes on the energy consumption is analyzed. Moreover, the different factors such as number of hops and bit error ratio (BER) for energy savings are investigated in a CMIMO-SMR-based multihop ad hoc network where the optimal number of hops and the BER relationship are derived by taking into account the transmission energy and the circuit energy, as well as the bit-recovery situation. In the simulation, it is demonstrated that CMIMO-SMR is more energy efficient compared with the existing works. Moreover, an adaptive algorithm for choosing the appropriate number of hops to minimize the energy consumption is designed when the end-to-end designated BER is required. The results demonstrate that the minimum energy consumption can be achieved by using the proposed algorithm without compromising the designated BER requirement at the destination.