A model of compress-and-forward system based on heterogeneous multi-relay network is presented, in which relays compress and encode the received analog signals and transmit them into digital signals, then forward to the destination over Gaussian noise channels with different powers. The destination jointly decodes the received digital signal and yields the estimation of the original signal. Theoretical analysis framework is presented and the expression of the system is derived based on the chief executive officer(CEO) problem of Gaussian source and Shannon channel capacity theory. Subsequently, the power allocation is proposed under the constraint of total system power to maximize the SNR performance. Simulation result verifies that, the SNR performance of the proposed compress-and-forward system outperforms that of the traditional amplify-and-forward system.