The utility model relates to an assembled yo-yo ball, which comprises two rotary discs, a connecting body and a yo-yo rope, wherein the rotary discs are composed of wheel hubs and alloy bodies connected with the peripheral parts of the wheel hubs, and the shaft centers of the wheel hubs are provided with screw holes. The outer edges of the screw holes at one side of one wheel hub which is opposite to the other wheel hub are provided with scarf-joint flanges, and the corresponding side surface of the other wheel hub is provided with scarf-joint concave rings corresponding to the flanges. Ball bearings are sheathed out of the scarf-joint flanges, and the inner rings of the ball bearings are tightly combined with the scarf-joint flanges. The connecting body is a screw rod which is screwed in the screw holes of the shaft centers of the wheel hubs and penetrated through the central holes of the scarf-joint flanges, the yo-yo rope is connected out of the ball bearings, and the opposite side surfaces of the two wheel hubs are provided with friction adding mechanisms. The utility model has the advantages of favorable running inertia, long endurance and fluent running, the yo-yo ball can be pulled and flung freely, and the assembled yo-yo ball is suitable for performance having high value part. The amusement and the impact resistance of the yo-yo ball are enhanced, and the service life of the yo-yo ball is prolonged.