The invention provides a locking device of a drill-collar-type instrument. The locking device comprises a metal ring, a pin shaft and a rapid locking head which are arranged in a matched mode, and a corrugated groove is machined in the metal ring and used for compensating the interval change between the metal ring and a drill collar during locking. According to the locking device of the drill-collar-type instrument, the structure is simple, and the reliability of locking of the drill-collar-type instrument is effectively improved.