Two strontium optical lattice clocks (Sr1 and Sr2) are being built at National Institute of Metrology(NIM) of China. Sr1was firstly evaluated in 2015, and later equipped with a new clock laser based on a 30 cm reference cavity, which helpedto improve its stability. Sr2 is built on a new campus of NIM, which has some different designs compared to Sr1, forexample, a permanent magnets based Zeeman slower, a differential pumping stage, and a robust laser system. A timeinterleaved self-comparison campaign of Sr2 of more than 7 days shows an up-time of ~90% and a measurement stabilityof 3.7×10~(15)/ ~（1/2） with a 10 cm ULE cavity based clock laser. The link between these two optical clocks, that consists oftwo fiber optical frequency combs and a 54 km fiber connection, are being constructed. The comparison of these twoclocks is planned in the near future.
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