We use ferromagnetic resonance to study the current-induced torques in YIG/heavy metal bilayers. YIG samples with thickness varying from 14.8 nm to 80 nm, with Pt or Ta thin film on top, are measured by applying a microwave current into the heavy metals and measuring the longitudinal DC voltage generated by both spin rectification and spin pumping. From a symmetry analysis of the FMR lineshape and its dependence on YIG thickness, we deduce that the Oersted field dominates over spin-transfer torque in driving magnetization dynamics.Introduction -Insulating magnetic materials have recently played an important role in spintronics, since they allow pure spin currents to flow without associated charge transport. Within the family of ferromagnetic insulators, yttrium iron garnet (YIG) holds a special place owing to several favourable properties, including ultra-low damping, high Curie temperature and chemical stability [1][2][3]. By growing an overlayer of heavy metal (HM), such as platinum or tantalum, several important spintronic phenomena have been explored in the YIG/HM bilayer system, including the magnetic proximity effect [4,5], spin pumping [6,7], spin Hall magnetoresistance (SMR) [8,9], spin Seebeck effect [10,11] and so on. Furthermore, the spin Hall effect in HM can convert a charge current into a transverse pure spin current, making it possible to manipulate the ferromagnetic insulator by spin transfer torque (STT). Recently, several groups have reported controlling the damping in YIG by applying a DC charge current in a Pt capping layer [12], by which spin-Hall autooscillation can be realized [13,14]. Replacing the DC current with a microwave current, the electrical signal in Pt can also be transmitted via spin waves in YIG [3]. In order to further explore the application of the YIG/HM system, it is necessary to understand the torque on YIG induced by the charge current in HM.