The invention discloses an interlocking device of a change-over switch. The change-over switch comprises a common side operation mechanism and a standby side operation mechanism; the interlocking device comprises a common side driving connection rod, a common side driven connection rod, a common side executing connection rod, a standby side driving connection rod, a standby side driven connection rod and a standby side executing connection rod. The common side driving connection rod moves along with a main shaft of the common side operation mechanism; the common side driven connection rod is connected to the common side driving connection rod; the common side executing connection rod is connected to the common side driven connection rod, and is mounted on a side plate of the standby side operation mechanism; the common side executing connection rod rotates by surrounding a second fulcrum on the side plate of the standby side operation mechanism; the standby side driving connection rod moves along with a main shaft of the standby side operation mechanism; the standby side driven connection rod is connected to the standby side driving connection rod; the standby side executing connection rod is connected to the standby side driven connection rod, and is mounted on a side plate of the common side operation mechanism; the standby side executing connection rod rotates by surrounding a first fulcrum on the side plate of the common side operation mechanism.