NiTi alloys are ideal candidates for aerospace actuators due to the shape memory effect activated by change of temperature [1]. Additive manufacturing technologies, such as laser powder bed fusion (L-PBF), can be used to produce NiTi actuators based on 3D modelling of laser-depositing powder material in successive layers [2]. However, significant uncertainties and challenges exist in relation to mechanical properties of additively manufactured parts due to the strong influence of process parameters on microstructure and mechanical behaviour [3]. The present work is related to a type of NiTi aerospace actuator which operates via torsion and axial loading-deformation [4]. The present work is focussed on development of macro- and micro-mechanical models for fatigue crack initiation of such actuators. The work is part of a larger project on the development of a computational model for process-structure-property-performance relationships to optimise the design of additively manufactured NiTi actuators [5]. In the present work, we focus on establishing the relationship between microstructure and mechanical behaviour (especially fatigue) for NiTi using crystal plasticity finite element (CPFE) modelling based on electron backscatter diffraction (EBSD). The transient cyclic behaviour of NiTi under combined axial-torsional loading, including phase transformation effects, is simulated using the Auricchio model, to capture the superelastic behaviour of NiTi [6]. A global-local modelling approach is adopted to combine the Auricchio (global) model with a local CPFE micromechanical model for fatigue crack initiation, with adoption of multiaxial (e.g. critical-plane) fatigue indicator parameters (FIPs) to estimate axial-torsional fatigue life. Local micromechanical CPFE models of combined torsional-axial loading of NiTi is implemented with microstructure-sensitive FIPs is also implemented to predict crack initiation. It is intended to adopt a recent melt pool based CPFE method for L-PBF to assess the effects of process-induced texture effects, e.g. build orientation, for design optimisation of the NiTi actuator fatigue response.