Measuring deuteration fraction in protostellar cores is considered as an important method for age determinations of protostellar cores, and the high deuteration fraction of up to 10% has been considered as evidence for high ages and strong support via magnetic field. In this talk, I will present 3D magneto-hydrodynamical simulations including the deuteration chemistry to explore how the deuteration fraction depends on the dynamical and chemical conditions. I will show that high deuteration fractions can be obtained under a large set of different conditions.