VO2 thin films were prepared from V2O5 films using post-deposition annealing in vacuum. The films obtained have been studied by using XRD, XPS, SEM, UV-VIS and electrical measurements. The results show that the samples prepared at the optimal conditions before and after phase transition the resistance of VO2 thin film changes about 103 orders and the transmittance of 900nm light change 40%. Different preparation conditions can change the phase transition properties in VO2 thin films. The structural properties of samples are improved but the phase transition properties are declined by the increase of annealing time and annealing temperature. The best reasonable annealing time and annealing temperature has been got by discussing the effects of annealing time and annealing temperature on the phase transition point and hysteresis width. Other factors that affect the optical and electrical properties in VO2 thin films have also been discussed.