The utility model relates to a securing anti-theft door, which is composed of a door body and a built-in lock arranged on the door body. A guard cover plate is arranged on the position of a locking hole exposed from the built-in lock of the door body; the locking structure is a coded lock when the guard cover plate is closed. The built-in lock is arranged in the lock case of the door body, and a box cover faced to the locking hole is the guard cover plate. A linkage piece can be arranged between the bayonet of the guard cover plate and the rotary lock plate of the coded lock. The guard cover plate controlled by the coded lock protects the lock core of the built-in lock and the locking hole from breaking. Only when the coded lock and the guard cover plate are firstly opened, the built-in lock can be unlocked with the key to increase the anti-theft effect.