Tungsten is the most effective dopant for reducing the phase transition temperature(tc) on per atomic percent basis. However, the tc reduction values reported until now is very dispersive from 9 to 36C/at.%w [46,47] compared the concentrated value about 21–24 C/at.%w for single crystals [48,49]. Some authors established the linear relationship between tc and x (x in WxV1_xO2) within experimental uncertainties. In our experiments, the phase transition properties were studied by DSC technology which were shown in Fig. 6(a) and(b). In Fig.6(c), a linear relationship between tc and x (from 0 to 0.025) was established, and the least square approximation gives a tc reduction efficiency of 21.96 K/at.%w. Compared with the literature, our value is in good agreement with those for tungsten doped VO2 single crystals. It is worth noticing that the tc for samples without doping was 55.5 C, which is far lower than the value for single crystal VO2 (68 C). The reason for the obvious decrease of tc might be the size effect or the oxygen vacancies caused by oxygen deficiency in VO2 crystal lattice since our samples were fabricated in reductive circumstance [1]. Oxygen deficiency would lead to the increase of electron concentration and decrease tc. Further reduction of tc was caused by the substitution of tungsten for vanadium.