Strengthen criteria can be used for strength evaluation of a construction operating in the conditions of complex stress. There are a lot of strengthen criteria for anisotropic materials suggested by different authors. The problem of choosing a correct criterion for some material is a very important problem. The most reliable approach is an experimental check. The author considers some modifications of famous Misses - Hill criterion for anisotropic materials suggested by some other authors and by the author of this article. The variant suggested by the author gives better results when comparing with the experimental data then the other variants of this criterion.