"We construct a Milky-Way model composed of a stellar disk and bulge embedded in a dark matter halo. All components are modeled as N-body systems with equal-mass particles using up to 8 billion particles in total, and each model is simulated for up to 10 Gyr. We find that halo spin is required to form a relatively short bar (~4 kpc) with a fast pattern speed (40-50km/s) and that the best-fit spin parameter is 0.06. Comparing our model with observations of the Milky Way Galaxy, we find that a disk mass of ~3.7x10^10M and an initial bulge scale length and velocity of ~1 kpc and ~300km/s1 fit best to the observations. We further find that the disk-to-total mass fraction (fd) is an important parameter. From our simulations, we find fd~0.45 for the best-fitting Milky-Way models."