The detection of Cosmic Dawn and the Epoch of Reionization is one of the most exciting fields in cosmology. The direct detection of these periods can only rely on the observation of red-shifted 21cm emission neutral hydrogen signal. One of the three main methods of detection is measuring the global spectrum of 21cm emission from Cosmic Dawn and the Epoch of Reionization. Here we review recent progress of existing and planned experiments aiming such detection including ground-based radio experiments such as BIGHORNS, EDGES, LACE, LEDA, MIST, REACH, SARAS 3, SCI-HI, PRI$^Z$M, and space low-frequency global spectrum experiments such as DARE, DAPPER, FARSIDE, Hongmeng. Among them, EDGES is the only experiment that claims to have observed a suspected Cosmic Dawn signal. However, the result is inconsistent with the standard cosmological model (Λ Cold Dark Matter, ΛCDM). If the detection is confirmed, it will be the first signal that mankind has detected from Cosmic Dawn, so as to fill the gap in the observation of cosmic evolution.