The software product line is one of the most effective strategies for reuse of large-scale software and rapid development of new software products with good quality levels. The variability modeling technique used to describe the commonality and variability of software product families is one of the most important techniques in software product line. Variability modeling plays an important role in the product line domain engineering and product line application engineering. However, it is difficult for modelers and engineers to choose one or more suitable modeling techniques from various variability modeling techniques. A systematic literature review of the variability modeling techniques in software product line reported from 1990s to 2011 is carried out. In this systematic review, the existing variability modeling techniques are analyzed and compared to help engineers and/or researchers to select the most suitable variability modeling techniques. Finally, the research trend of variability modeling technique is given, and the prospects for future research and suggestions for possible extensions are also discussed.