With the advancements in laser technology and improvements of the operation robustness, the fountain clocks can not only be used as frequency standards to calibrate atomic time scales, and improve the long-term stability and accuracy, but also be used to steer a hydrogen maser as a time-keeping clock. The ground state hyperfine transition of rubidium atoms, as a secondary representation of the second definition, has the advantages of small collision cross-sections and highly robust cooling lasers. It is a better candidate for commercial clocks. The prototype of a commercial rubidium fountain clock developed at the National Institute of Metrology (NIM) with a bi-metal microwave-vacuum integrated Ramsey cavity to increase the temperature adaptability of the system. A miniaturized optical system and a cage structure detection light system to improve operational reliability. A long-term quasi-continuous operation with an operation rate of 97. 5% in a year is realized. Though the one-year comparson tese, the long-term fractional frequency instability achieves 3. 7×10 -16 for the comparisons between the Rb fountain clock and NIM5 cesium fountain clock. The frequency instability of a single fountain clock is better than 2. 6×10 -16 .