The invention relates to a small ball-end milling cutter for finish machining. The ball-end milling cutter is composed of a cutter clamping handle, a cutting part and a transition part located between the cutter clamping handle and the cutting part, wherein multiple spherical curve cutting edges are uniformly distributed on the cutting part; the ends of the spherical curve cutting edges are intersected on the vertex of the milling cutter; along the rotation direction of the milling cutter, the front tool face of each spherical curve cutting edge is a plane, the first rear tool face of each spherical curve cutting edge is a spherical surface, and the second rear tool face of each spherical curve cutting edge is a plane; and the ball-end milling cutter is characterized in that: the intersection lines of the front tool face and spherical surface of each spherical curve cutting edge form a spherical curve cutting edge, the front angle [alpha] of each spherical curve cutting edge is greater than or equal to -20 degrees and less than 0 degree, the center angle [beta] of each spherical curve cutting edge is greater than or equal to 90 degrees and less than or equal to 120 degrees, and the cutting radius of each spherical curve cutting edge is greater than or equal to 0.05 mm and less than or equal to 1 mm. The ball-end milling cutter is particularly applicable to the micro finish machining of a hard and fragile workpiece with a complicated curve shape so as to obtain high surface quality and high cutting efficiency.