Direct-driven Electrical Hydrostatic Actuator (D-EHA) is a novel actuator for large aircraft Power-By-Wire (PBW) system.Achieving high dynamic response is an important task for D-EHA.In this paper,a tubular oscillating motor with improved Halbach array and non-ferromagnetic mover tube is proposed for high-dynamic system.Its structure and operating principle is first clarified.Then,focusing on the novel magnet array,analytical modelling is put forward and validated by FEM simulation.Comparisons with common used quasi-Halbach design over flux distribution,flux density and thrust are conducted.The results indicate that this novel magnet design has superior thrust and dynamic performance over traditional ones,especially for oscillating motor with relatively small stroke.