We report the STAR measurement of phi meson production in Au + Au and p + p collisions at root s(NN) = 200 GeV. Using the event mixing technique, the phi spectra and yields are obtained at mid-rapidity for five centrality bins in Au + Au collisions and for non-singly-diffractive p + p collisions. It is found that the phi transverse momentum distributions from Au + An collisions are better fitted with a single-exponential while the p + p spectrum is better described by a double-exponential distribution. The measured nuclear modification factors indicate that phi production in central An + An co...