Abstract: The Kelvin-Helmholtz instability (KHI) is one of the hot issues in plasma physics, which has a non-negligible role in space plasma and magnetic confinement fusion. In this paper, a systematic numerical simulation study of the electron-scale KHI in magnetized shear flow is carried out in the subrelativistic case by using a two-dimensional electromagnetic particle simulation method. Emphasis is placed on analyzing the effects of the direction and strength of the applied magnetic field on the instability development and nonlinear evolution. The results show that different external magnetic fields have significant effects on the nonlinear structure of KHI, and overall the external magnetic field is inhibiting the development of KHI. No obvious KHI phenomenon is seen under the external magnetic field perpendicular to the shear velocity, but it excites multimode coupled plasma oscillations in the direction of the magnetic field, while magnetic reconnection and vortex magnetic island structures are observed in the shear plane. In addition, the energy spectrum of the self-generated magnetic field in the saturation phase is obtained, and the energy spectrum characteristics are consistent with the spectral power-law distribution presented by the turbulence spectrum.