Biochar is an ecological carbon-negative material. Adding an appropriate amount of biochar to concrete can improve the mechanical properties and durability of concrete. However, there are still controversies over whether biochar can be used as a pozzolanic material for concrete and whether biochar has pozzolanic activity. In response to this, this paper conducts a literature review and comprehensive analysis on aspects such as the pozzolanic activity of biochar, the impact of biochar on the mechanical properties of concrete, and measures to improve the pozzolanic activity of biochar. The results show that biochar has pozzolanic activity, and its pozzolanic activity is not affected by the loss on ignition, while the reactive SiO2 content is the decisive factor for the pozzolanic activity of biochar. The high pozzolanic activity of biochar can promote the pozzolanic reaction and hydration reaction, which is beneficial to the compressive strength of concrete. Controlling the pyrolysis temperature and fine grinding treatment can help to improve the pozzolanic activity of biochar, but the impact of activation treatment on the pozzolanic activity of biochar still requires in-depth research.