The explosive growth of the digital data brings great challenges to the relational database management systems in addressing issues in areas such as scalability and fault tolerance. The cloud computing techniques have been widely used in many applications and become the standard effective approach to manage large scale data because of their high scalability, high availability and fault tolerance. The existing cloud-based data management systems can't efficiently support complex queries such as multi-dimensional queries and join queries because of lacking of index or view techniques, limiting the application of cloud computing in many respects. This paper conducts an in-depth research on the index techniques for cloud data management to highlight their strengths and weaknesses. This paper also introduces its own preliminary work on the index for massive IOT data in cloud environment. Finally, it points out some challenges in the index techniques for big data in cloud environment.