The purpose of this study was to determine the elastic modulus and fracture strength of Polylactic acid/Hydroxyapatite nanocomposite. Due to the biodegradability and excellent mechanical properties, the PLA/HA nanocomposite can be used as a porous scaffold constituent. Porous scaffolds are three-dimensional polymeric porous structure with higher porosities and a homogeneous interconnected pore network, which are highly useful for tissue engineering. The mechanical behavior of PLA/HA nanocomposite will be predicted through a multiscale modeling framework, focussed at two separate macro and nano length scales. At the nanoscale Using molecular simulations, the PLA/HA interface adhesion quality and Interphase thickness were determined by PCFF-INTERFACE and Dreiding forcefields. It was observed that Interphase would be formed with a 0.4 nm thickness, and the PLA/HA interface adhesion can be considered as fully bonded. The information derived from the nanoscale will then be used to describe the behavior of macro-level models of the PLA/HA nanocomposites. At this scale, Firstly, a Representative Volume Element (RVE) for PLA/HA nanocomposite was identified, whereby the polycrystalline hydroxyapatite mineral components were separately dispersed. Using an appropriate homogenization strategy, this approach will predict the elastic modulus of the PNC under periodic boundary conditions. To predict the fracture strength of PNCs, we discretized a novel phase-field damage model for implementing as user subroutines UEL in the finite element software Abaqus. Furthermore, by identifying a new technique to use the Phase-field damage model on the macro-scale, the fracture strength of the PLA/HA nanocomposite is determined at different volume fractions. Keywords: Polylactic acid, Hydroxyapatite, Nanocomposite, Phase-field model, Molecular Dynamics, Finite Elemenet mode