The invention relates to the technical field of mechanical equipment, in particular to a flexible steering mechanical arm with a locking device. The flexible steering mechanical arm comprises a jointball, a supporting ring, an expansion link and clamping jaws. Four supporting pillars are evenly arranged at the top of the supporting ring. A movable block capable of moving is arranged on the supporting pillars. The locking device is fixedly arranged on a support. According to the flexible steering mechanical arm with the locking device, the movable block can be driven to move by transversely moving a first moving rod and a second moving rod, a convex block on the movable block drives a connecting rod in a through hole to deflect, and therefore the joint ball can be driven to rotate, the effect of adjusting the joint ball at will is achieved, the direction of the expansion link located below the joint ball can be adjusted at will, the clamping range of the clamping jaws can be widened, and the mechanical arm is made more flexible. Meanwhile, the flexible steering mechanical arm is simple in structure and the service life of the mechanical arm is greatly prolonged.