The recent evaluation of the second cesium fountain NIM5 at National Institute of Metrology(NIM) shows a total
relative uncertainty of 2×10-15. The strontium optical clock project has successfully transferred atoms from broad line
cooling to narrow line cooling. About 10788Sr atoms have been cooled down to 2uK, ready to be loaded into 1
dimensional (1D) optical lattice. The clock transition interrogation laser is locked to a horizontally oriented high finesse
cavity. The linewidth of this laser is reduced to 100Hz level. A fiber based optical frequency comb is being built, which
can be used to synthesize ultra-stable microwave frequency for the fountains in the future.