An atomic clock with excellent long-term stability is important for maintaining the Local Atomic Time (TA(k)). The ⁸⁷ Rb atomic fountain clock has the potential to fulfill these characteristics. It is required to operate continuously, similar to commercial cesium beam clocks and hydrogen masers. This paper describes the design and preliminary operation results of an ⁸⁷ Rb atomic fountain continuous clock ( ⁸⁷ RFCC) developed at the National Time Service Center (NTSC) of the Chinese Academy of Sciences. We adopted some improved design aspects and suppressed Majorana effect and microwave leakage to enhance the clock’s stability. Its continuous operation has been improved owing to the advantages of the high-reliability optical system and servo high-resolution offset generator (HROG) algorithm. We presented an algorithm for the 5 MHz/1 PPS signal output of the ⁸⁷ RFCC through the HROG. The ⁸⁷ RFCC exhibited a frequency stability of 1.91×10 ^-13 τ ^-1/2 , reaching 4.7×10 ^-16 at 200000 s. We referenced the 1 PPS output signal to the UTC(NTSC) and obtained the relative phase fluctuation of the ⁸⁷ RFCC, which was within ±1.75 ns for approximately 90 days. We estimated the preliminary drift of the ⁸⁷ RFCC relative to the UTC(NTSC) for three different periods at 0.000019±0.00148 ns/d/d, 0.00119±0.00182 ns/d/d, and -0.00155±0.00060 ns/d/d and discussed the results. During the 90-day evaluation period, although the frequency of the ⁸⁷ RFCC relative to the UTC(NTSC) had changed, it still exhibited a low drift compared to cesium beam clocks and hydrogen masers, which highlights its potential for excellent long-term stability. The ⁸⁷ RFCC investigated here has the potential to improve the local time scale.

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