In order to solve the problem that weak signal is difficult to detect in very low frequency and ultra-low frequency communication, a low noise preamplifier for low frequency is designed. Firstly, the noise model of amplifier is established and the noise sources and noise matching are analyzed, then the design points of the low noise amplifier circuit are described in detail, and a multi-layer shielding design method is proposed. Through simulation and experimental measurement, it is concluded that at 1kHz~1MHz, the voltage gain can reach 38dB; at 1kHz, the equivalent input noise is 0.99nV/√HZ, the noise coefficient reaches 0.76dB. The noise performance is greatly improved, it can meet the performance design requirements of low noise amplifier and can realize the effective reception of weak signal in VLF and VLF long-distance communication.