To deal with a sharp increase in transmission energy consumption due to the presence of a large number of secondary users ( SUs ) , an energy-efficient cooperative spectrum sensing results transmission scheme is proposed for cognitive radio systems. First, a cluster-based structure is introduced into the sensing results transmission scheme to reduce the transmission power. Then, the centralized sensing results transmission model is employed, and the non-fixed code rate Luby transform ( LT) code is selected as the channel coding since its code rate can dynamically adapt to channel conditions and therefore avoid unnecessary redundancy in the transmission power. Furthermore, an improved optimal degree distribution ( ODD ) is designed for the LT code. The simulation results show that the choice of the appropriate parameters in degree distribution is very helpful for the LT code to achieve a promising performance. The ODD with optimized parameters can achieve more than 2 dB performance gain than other typical degree distributions when the bit error rate ( BER) is 10-3 . The energy consumption of the proposed scheme is not only at least 71. 4％ lower than that of the non-coding system, but also lower than that of the convolutional coding system with different code rates. Meanwhile, the energy consumption can be further reduced in the case that a suitable clustering method is selected.