Soft magnetic materials such as FeSi steels are widely used in electrical transformers, magnetic actuators and many other electrical systems thanks to their excellent electromagnetic properties and low cost. In this silicon steel family, the high Si content FeSi-6.5% has shown the best potential in magnetic device applications due to its very low hysteresis and eddy-current losses. However, its employment has been limited due to its very brittle nature and poor workability. Recent works have shown that the Selective Laser Melting (SLM) was an ideal candidate for manufacturing parts with this material [1]. This work presents a numerical approach for the determination of residual stresses and distortions of parts manufactured in FeSi6.5% by SLM. The methodology, based on finite element models, uses a transient thermo-mechanical analysis combined with element activation technique of macro-layers, i.e. groups of typically tens powder layers. For each macro-layer, an equivalent heat source determined from the process parameters is applied uniformly and deformation and stresses are computed for each heating/cooling cycle. This strategy is used in order to predict the residual stresses and distortion of a demonstrator built in FeSi-6.5 by SLM. The structure is made of thin-walls with an Hilbert pattern cross-section, which is known to reduce the electromagnetic losses. The thermal and mechanical material temperature-dependant properties, required for the transient process simulation model, were measured experimentally on FeSi-6.5% SLM samples. The calculated residual stress distributions and distortions computed with the transient thermo-mechanical approach are compared with results obtained using the Inherent Strain method and experimental measurements.