Adaptive feedback cancellation is an effective way to suppress echo howling in hearing aids. However,when the external input signal is correlated with the receiver input signal, the estimate of the feedback path contains a large error. This paper proposes a linear prediction-parallel gradient projection algorithm,which generates a FIR filter to obtain the decorrelation signal by linear prediction of the output signals. The decorrelation signal is then used to build a convex optimization equation. With the parallel gradient projection algorithm, the equation is solved to evaluate the echo path. Simulation results show clear improvement in convergence, stability and precision.