A novel tunable optoelectronic oscillator (OEO) based on a photonic radio frequency (RF) phase shifter is proposed and analyzed, which consists of a dual-drive Mach-Zehnder modulator (DMZM), a 90° hybrid coupler and a tunable microwave amplifier (TMA). This tunable OEO has a simple configuration, and the frequency of the oscillating signal can be tuned by adjusting the amplification factor of the tunable amplifier. The simulation results show that the maximum frequency shift from the center oscillation frequency is 1.48 MHz when the amplification factor of the TMA is set at 10.