Noise cancellation is a common technology in the design of low noise amplifiers (LNA). Solving the contradiction between noise and power consumption is the most difficult challenge during the design process. A new noise cancellation structure is proposed in this study. Noise in the main and auxiliary branches is eliminated by adding a feedback loop between the main and auxiliary branches, without increasing power consumption. Based on a 180 nm CMOS technology, a wideband low noise amplifier with the noise cancellation structure is designed.Simulation results show that the bandwidth of the LNA is 0.4-2.36 GHz, both S11 and S22 are less than -10 dB,S12 is less than -30 dB, the maximum S21 is 14.5 dB, the noise factor is 2.20-2.34 dB, and the power consumption is 9 mW.