Control of octahedral rotations in the ABO3 perovskite oxides has been of great interest due to its potential in
rationally discovering and designing new multifunctional phases. In this study, we show that octahedral rotations of the SrRuO3 films can be controlled by oxygen vacancies as well as by interfacial coupling, which further determines the physical properties. Half-integer reflections using high-resolution synchrotron x-ray diffraction were carried out to determine the octahedral rotation pattern of SrRuO3 films on SrTiO3 substrates. The transition of RuO6 rotation pattern accompanied by the structural change from monoclinic P21/m to tetragonal F4/mmc can be understood from the preference of oxygen vacancies in the SrO atomic plane and the coupling of octahedra across the interface between film and substrate. The field angle dependence of magnetoresistance further confirmed the structural phase transition with changes in octahedral rotations. The monoclinic phase has the uniaxialmagnetic easy axis 30° away from the  direction towards the  direction while the tetragonal phase has uniaxial magnetic easy axis along the fourfold axis which is perpendicular to the film surface. This study demonstrates the ability to control the octahedral rotations in perovskite films and its importance when designing thin films and multilayers with desired functional property.