The emergent cooling technologies based on the caloric effect provide a green alternative to the conventional vapor-compression one which brings about the serious environment problem. However, the existing caloric materials are much inferior to their traditional counterparts in cooling performance. Here we report the colossal barocaloric effect in liquid-solid-transition materials, i.e. n-alkanes. Their excellent cooling performance is superior to those for existing caloric materials and comparable to those of traditional refrigerants. Theoretical calculations suggest the liquid state n-alkanes has huge configuration entropy characterized by large dispersion of bond lengths. Appling pressure significantly reduces the configuration entropy and eventually induces the liquid-solid-transition, leading to the colossal barocaloric effect. This work provides promising refrigerants for caloric cooling technology, and opens a new avenue for exploring colossal barocaloric materials.