It is well known that the binary diagram of silicate-water and the residual magma-solution illustrated and proposed by Niggli are the theoretical basis of post-magmatic hydrothermal metallogeny. Based on recent experimental data on the silicate-water system, the calculation results derived from the experiments and the geological facts, it can be proved that Niggli's binary diagram of silicate-water and the vapor tension curve in the process of evolution of magma are unreasonable. The fact is that the miscibility between silicate and water is not unlimited. The crystallization process is terminated at the solidus and before reaching the solidus the surplus water escapes in the vapor state from the magmat therefore, the evolution process can not produce residual solutions in which water is the main component. From the above discussion the conclusion can be reached that Niggli's binary diagram is groundless and that residual magma solution is inexistent.Consequently, post-magmatic hydrothermal metallogeny is without foundation.