At Peking university, In Yunquan Liu and Qihuang Gong’s group, they used the advanced Cold-Target Recoil Ion Momentum Spectroscopy (COLTRIMS)setup to investigate the electron correlation dynamics of strong-field double ionization of atoms. They have performed fully differential measurement on strong-field double ionization of Xeby 25 fs, 790 nm laser pulses in intensity region of (0.4~3)×1014 W/cm2. They observed that the two-dimensional correlationmomentum spectra along the laser polarization direction show a non-structured distribution for double ionization of Xe over a wide range of laser intensities decreasing from 3×1014 W/cm2 to 4×1013 W/cm2, as shown in Fig. 1. The electron correlation behavior is remarkably different with the low-Z rare gases, i.e., He, Ne and Ar. They have found that the electron energy cutoffs increase from 2.9 Up to 7.8 Up when decreasing the laser intensities from sequential double ionization to nonsequential double ionization regime. The experimental observation indicates that multiple rescattering play important role for the generation of high energy photoelectrons.They have further studied the shielding effect on the strong-field double ionization of high-Z atoms.