The armature-rail contact interface affects the characteristics of armature startup in the pulsed high current linear driver. Furthermore, the armature startup has an influence on the system efficiency and lifetime. This paper discusses the effect of armature surface morphology on armature startup. In the experiments, a high-speed camera was set up to observe the armature startup. Combined with the finite element software ANSYS, the pre-tightening force and contact status were simulated. Besides, the electromagnetic pressure and current density were also obtained by simulation. The results show that groove increased the flexibility of armature and the homogeneity of current distribution was improved by the current skin effect. Owing to the increasing pressure, the groove armature startup was delayed and its contact resistance reduced. The results have important significance to improve contact condition and reduce erosion.