Rotary clocking is a low-power technology for multi-GHz clock generation and distribution. In this paper, a sensitivity analysis of the Rotary Traveling Wave Oscillator (RTWO) to process variations is presented based on a 90 nm technology. The analysis is focused on the effects of 1) multiple process corners, 2) power supply fluctuation, 3) chip temperature change, 4) the variations of the RTWO transmission line width and separation, on the operating frequency and power consumption of the RTWO. The individual analysis of these factors is presented as well as a Monte-Carlo based analysis to analyze the comprehensive effects of the process parameter variations and process corners. SPICE simulation results show that the RTWO exhibits a natural robustness to resist these on-chip variations.