Cement concrete is sensitive to cracking during service due to its brittleness and early susceptibility to shrinkage and deformation, further leading to the water seepage and leakage of concrete structure. The timely and effective repair of water leakage in cracked concrete has attracted recent attention in engineering. Superabsorbent polymer (SAP) hydrogel is a new type of self-sealing agent developed in recent years, which has the characteristics of rapid water absorption and significant volume expansion, and has a promising application potential in crack healing and sealing in humid environment. This review represented the basic design method of self-sealing cement-based materials based on hydrogel, discussed the working mechanism of SAP hydrogel as self-sealing agent and its effect on the anti-permeability, mechanics and durability recovery of concrete, and summarized the evaluation method of crack healing and sealing efficiency. In addition, the main challenges and future directions of hydrogel based crack self-sealing technology were also proposed.