The Radioactive Ion Beam (RIB) physics is one of the most active fields in nuclear physics researches today, and the External Target Experimental Hall (CSRm-ET3), which is downstream of the second Radioactive Ion Beam Line in Lanzhou (RIBLL2), is a very powerful tool for improving the research works in this field. The CSRm-ET3 is equipped with many different kinds of high performance detectors and associated electronics/data acquisition system, and all the products including charged particles, neutrons and γ-rays can be measured simultaneously with high precision. The CSRm and RIBLL2 can provide stable or RI beams with the energy of several hundreds AMeV, and the kinematically complete measurements for reaction products can be realized in the CSRm-ET3, which allows the studies for many important topics, such as the properties of short-lived isotopes, the property of nuclear matter and the exploration of new reaction mechanism.