In this paper, we propose a simple and effective method to manipulate photonic spin accumulation with an applied magnetic field. When a linearly polarized Gaussian light beam is reflected from the prism-air interface at the Brewster angle, the magnitude and direction of the photonic spin accumulation can be flexibly modulated by adjusting the applied magnetic field. Importantly, the maximum displacement of photonic spin accumulation can reach about 39.14 μ m , which provides the opportunity to directly observe photonic spin accumulation without weak measurements. These findings may hold potential applications for manipulating and detecting the electron spin current, leading to the development of a new spintronic device. [ABSTRACT FROM AUTHOR]