Network virtualization, known as a promising technique, has emerged as an effective method to overcome the ossification of the Internet. By enabling the co-existence of multiple heterogeneous Virtual Networks (VNs) over a shared infrastructure, network virtualization exhibits better flexibility. A crucial problem is Virtual Network Embedding (VNE), namely embedding the virtual networks to the substrate network efficiently. Because it is an NP-hard problem, many heuristic algorithms have been developed. However, their efficiency is not high, which makes them unsuitable for real-time multimedia services. Thus, we propose an efficient virtual network embedding algorithm based on subgraph, which takes the load status of substrate links and the network connectivity into consideration. With the proposed algorithm, the computation complexity is reduced and the processing time for each request is shortened. Our simulation results reveal the better efficiency of the proposed algorithm compared to the existing ones.