The invention discloses a bulb end milling cutter and a milling processing four-shaft associated device thereof. An S-shape bulb edge (1) is connected with a spiral circumferential edge (5), a bulb edge front face is connected smoothly with the circumferential edge front face (6), the bulb rear face (3) is connected with the circumferential edge rear face (7), and the bulb edge spiral groove (4) is connected with the circumferential edge spiral groove (8); the front angle of the bulb edge front face (2) is a rather big positive front angle, and is distributed with a small-big-small mode from inside to outside; the milling processing four-shaft associated device of the bulb end milling cutter comprises a latch bed (10), a horizontal longitudinal X axis straight-line motion flat stage (11), a horizontal transversal Y-axis straight-line motion flat stage (12), a vertical Z axis straight-line motion flat stage (13), a workpiece rotating shaft (14), and a front tool face milling head (15), and a rear tool face milling head (16). The invented devices are provided with characteristics of stable milling, smooth chip removal, simple structure, low cost, moderate price, and economic.