In this paper, Bridcage type RF coils used widely as RF coils for MRI and its applicable type, spiral type RF coil are analyzed and designed using FDTD method. In low tesla (IT, 1.5T) MRI system, several tools have been used for the analysis and design of the RF coils for MRI. This includes, so-called, LC equivalent circuit method for predicting the resonance frequency of the coil and the Biot-Savart law to determine the field distribution within the coil. Both of the circuit analysis and Biot-Savart law are low frequency techniques. Therefore, at high frequency applications, the circuit model approximation breaks down because the coil geometry is a significant fraction of the wavelength. In this paper, we analyzed and designed RF coils for 3T MRI using FDTD method. This method is a full wave analysis and very accurate at low and high frequencies. Also, this RF coils are actually fabricated and FDTD models of RF coils for MRI are proven.