Laser powder bed fusion (LPBF) additive manufacturing (AM) is an advanced fabrication technique broadly adopted in the industry because it enables the 3D-printing of arbitrarily complex components [1]. However, during the LPBF process residual stresses are generally induced by sharp thermal gradients and the strong mechanical constraining to the substrate [2]. Such stresses can cause large warpages and cracking of the AM builds, compromising the component qualification. To address this challenge, the annealing heat treatment process after the LPBF fabrication is a good solution for the stress release allowing for the development of visco-strains at elevated temperatures. Thereby, this work is focused on the numerical simulation of the annealing heat treatment of Ni-based GH4099 super-alloy components made LPBF. The scope of this study is the thermos-mechanical analysis of different annealing conditions (e.g. temperature and dwell time) on the residual stresses and deformations of AM-parts. To achieve this goal, several bridge structures are fabricated by LPBF and different annealing heat-treated conditions are applied. After cutting from the substrate, the final distortion of all the AM-parts is measured using a 3D-scanner. Once calibrated, the numerical model has proven a remarkable agreement with the experimental measurements. The validated model is used to define the optimal process window for annealing heat treatment by exploring several processing conditions.