The main objective of the presented work is to develop an integrated computational environment that predicts final part properties made of semicrystalline thermoplastics. This objective is fulfilled by adopting the following two-step approach: 1) identification of an analytical scheme to correlate crystallization parameters with engineer properties; 2) apply the analytical scheme to the numerical simulation to study the polymer and final properties of the part. In this work the crystallization evolution in cooling phase, mainly influenced by thermal gradients, and its effect on the final part properties are investigated. The numerical method, crystallization models and their implementation into numerical software are described as well as the experimental data.