Ba0.6Sr0.4TiO3 dielectric thin films doped by Cr(0, 1, 2.5, 5, 10 mol%) (BSTC) were prepared by radio frequency magnetron sputtering on Pt/Ti/SiO2/Si substrates. The structure and morphology of the BSTC thin films were studied by atomic force microscopy and X-ray diffraction. The effect of Cr doping on the dielectric properties of BST thin films were analyzed. The results show that the dielectric loss of Cr doping BST thin films is lower than that undoped, and the tunability increased with Cr doping. The thin film doped with 5 mol% Cr has the best dielectric properties. The tunability, loss and figure of merit (FOM) at 1 MHz were 38.9%, 0.0183, and 21.3, respectively.