Firstly, a third-order extended state observer(ESO) with an inverse hyperbolic sine function is designed. The stability of a third-order ESO error system is proved with the Lyapunov function. Then, the ESO parameters’ values during the initial phase are determined with the inverse hyperbolic sine function in order to restrain the derivative peaking phenomenon. Finally, the simulation results show that the ESO can obtain higher precision estimations of all the state variables and non-linear disturbance and restrain the derivative peaking well.