Aiming at the influence of the time consumption of the information transmission process and the channel estimation error on the energy efficiency of the network， a joint optimization method of full-duplex cognitive relay network based on nonlinear energy harvesting was proposed. The proposed method was based on the use of nonlinear energy harvesting in the relay and consideration the imperfect Channel State Information （CSI）. Firstly， the energy efficiency non-convex optimization problem was transformed into two convex sub-optimization problems to obtain the transmission power of the secondary user and the relay as well as the collected energy. Secondly， under the condition that the primary user interference threshold was guaranteed and the optimal transmission power was non-negative， the range of transmission channel capacity was obtained. Finally， the transmission power was substituted into the expression to obtain the time related objective function， and the Hessian matrix was used to prove that the objective function was a convex function， the optimal transmission time and power splitting factor were calculated， and the optimal solution of energy efficiency was obtained. Experimental results show that under the same conditions， the energy efficiency of the proposed joint optimization method is about 84.3% higher than that of only optimizing the transmission power. At the same time， it is verified that when the channel estimation error factor is 0.01， the energy efficiency of the network is reduced by about 1.9% by using the proposed method.