The invention provides a four-axis linkage machining mechanism of a numerical-control machining center and an operating method of the four-axis linkage machining mechanism. According to the technical scheme, the four-axis linkage machining mechanism of the numerical-control machining center comprises an operation chamber, a machining spindle and a machining table; the machining table is composed of a rotary table tailstock, a main part positioning device, an auxiliary part positioning device, a clamp body and a rotary table body; and a plurality of hydraulic supporting cylinders and a plurality of hydraulic pressing cylinders are further arranged on the clamp body. By the adoption of the four-axis linkage machining mechanism, the problems that a workpiece cannot be clamped easily, multiple procedures are needed for machining, and the precision is difficult to control are mainly solved, and a machining mode requiring multiple machine tools is changed, so that the numerical-control machining mechanism which can achieve rapid machining and high-precision machining and simplify machining procedures is obtained. The four-axis linkage machining mechanism is suitable for machining parts which are huge in boundary dimension, light and thin in structure and prone to deformation, and thus the phenomenon that clamping is difficult is avoided. The mechanism has a strict form and location tolerance requirement, the requirements for assembly and detail treatment of a system are improved, and the effect that the stability of the product quality and high efficiency are still kept in long-time continuous production is guaranteed.