Network virtualization (NV) is considered as an enabling tool to remove the gradual ossification of current Intet. In the network virtualization environment, a set of heterogeneous virtual networks (VNs), isolat-ed from each other, share the underlying re-sources of one or multiple substrate networks (SNs) according to the resource allocation strategy. This kind of resource allocation strat-egy is commonly known as so called Virtual Network Embedding (VNE) algorithm in network virtualization. Owing to the common sense that VNE problem is NP-hard in nature, most of VNE algorithms proposed in the lit-erature are heuristic. This paper surveys and analyzes a number of representative heuris-tic solutions in the literature. Apart from the analysis of representative heuristic solutions, a taxonomy of the heuristic solutions is also presented in the form of table. Future research directions of VNE, especially for the heuris-tics, are emphasized and highlighted at the end of this survey.