Advances of repetitively operated relativistic backward wave oscillator (BWOs) is presented. Improvement of operating stability of BWO was obtained based on our earlier BWO operating at 100 Hz repetitive rates through changing the cathode and beam collector. An oil-immersed graphite cathode and water-cooled beam collector were introduced to increase output stability. Experimental results indicate that BWO's efficiency is up to the highest 33 % at optimum diode voltage, which is consistent with numerical simulations. The BWO could stably operate at rates of 100 Hz with microwave output power of over 1 GW, and the continuous time was up to 5 seconds.