The invention discloses a sharp instrument box cover with a sealing function and a needle head rapid cutting function. The box cover comprises a hemispherical block, a box body, a plastic bag, a coverplate, first heating strip blocks, cuboid frames, electric push rods, strip-shaped cutters, strip-shaped grooves, pin hole plates, butt joint battens, strip-shaped through holes, installation grooves, second heating strip blocks and operation rods. The mode that a cutter is manually operated to cut off a needle head is changed, so that the needle head is quickly replaced, the length of a cuttingedge is increased, multiple needle heads can be cut off simultaneously, the plastic bag containing the needle head in the box body is conveniently packaged, centralized placement is facilitated, and the needle head is prevented from falling off when the plastic bag is taken out; the operation rods at the corresponding positions are pressed by two hands respectively, so that the first and second heating strip blocks with heat move towards each other, and a bag body on the top of the plastic bag in the cuboid frames is easily extruded and attached between the first and second heating strip blocks; by means of the hot melting of the plastic bag, the effect of sealing the opening of the plastic bag is achieved.