  During the long term evolution of globular clusters (GCs), a part of member
stars are lost to the field. The recently found nitrogen-rich (N-rich)
metal-poor field stars are promising candidates of these GC escapees, since N
enhancement is the fingerprint of chemically enhanced populations in GCs. In
this work, we discuss the possibility of identifying N-rich metal-poor field
stars with the upcoming China space station telescope (CSST). We focus on the
main survey camera with NUV, u, g, r, i, z, y filters and slitless spectrograph
with a resolution about 200. The combination of UV sensitive equipment and
prominent N-related molecular lines in the UV band bodes well for the
identification: the color-color diagram of (u-g) versus (g-r) is capable of
separating N-rich field stars and normal halo stars, if metallicity can be
estimated without using the information of u-band photometry. Besides, the
synthetic spectra show that a signal-to-noise ratio of 10 is sufficient to
identify N-rich field stars. In the near future, a large sample of N-rich field
stars found by CSST, combined with state-of-the-art N-body simulations will be
crucial to decipher the GC-Galaxy co-evolution.
