The invention discloses a neuron adaptive harmonic current detection circuit based on a low pass filter, comprising an adding circuit, an integrating circuit, three phase inverting circuits, a scaling circuit, two multiplying units and a low pass filter circuit. On the basis of a neuron adaptive algorithm, the invention provides a neuron adaptive harmonic current detection circuit based on the low pass filter; the low pass filter is added, thereby not only improving circuit dynamic performance, quickening convergence rate and being beneficial to system stability, but also improving system steady-state behavior. The invention can detect harmonic current in non-linear load current in real time with high accuracy, can trace and detect varied load current, is not sensitive to the change of power supply frequency, and can be applied to real-time monitoring, compensation and control of an electrical power system.