The invention discloses a machining method of a shell. The machining method comprises the steps that the shell is clamped to a clamp; the deviation between a first center of the shell and a datum center of a computer numerically-controlled machine tool is detected by utilizing a probe, and the datum center is compensated according to a result obtained through detection; a second center is obtained; whether a difference value between the second center and the first center is within a preset difference value range or not is judged, if yes, a material, with a preset thickness, of a side frame ofthe shell is removed, and if no, the step of obtaining the second center is repeated. According to the machining method of the shell, the second center of the shell is detected repeatedly through theprobe, so that the difference value between the second center and the first center is decreased as much as possible, therefore the removing thickness of the two sides or the periphery of the shell tends to be the same as much as possible when the material on the side frame of the shell is removed, it is ensured that the thickness of the finally machined wall of the shell tends to be the same, andthe shell reliability is greatly improved. The invention further provides the shell and a mobile terminal.