In a network emulation system of the present invention, a packet transmitted from a user-mode application program is intercepted at a kernel-mode network driver and transferred to a user-mode emulation module to perform emulation, and, thereafter, the corresponding packet is returned to the network driver. The emulation module emulates a network characteristic of a multi-node environment through configuration of virtual network topology. At this time, the emulation module classifies the intercepted packets for each flow, stores the classified packets in a plurality of real queues, stores a virtual packet corresponding to the real packet in a virtual queue, and transfers the virtual packet to a virtual network including a plurality of virtual nodes to emulate the network.