Self-hardening sand lock cylinder of cold-box core

The utility model discloses a self-hardening sand lock cylinder of a cold-box core, which comprises the cold-box core (1) and a core (2), wherein the cores (1, 2) adopt molding sand, are molded by the molding sand according to castings and are respectively an upper die and a lower die, a core bar (4) is mounted in a through hole between the cores (1,2), and self-hardening resin is filled on the periphery of the core bar (4) so as to form a self-hardening core (3), the integral core assembly is turned after the self-hardening core (3) is solidified with certain strength, and then the cod-box core is locked by aid of the self-hardening core and the core bar. In addition, the lock cylinder is firm, and is high in dimension precision, easy in manufacturing and convenient for use.