Jinduicheng, Nannihu, Shangfanggou, Shijiawan, Leimengou, Donggou and Yechangping molybdenum deposits occur in Yanshanian small-size porphyry granite of eastern Qinling molybdenum belt. In order to summarize metallogenic regularity and establish mineralization model so as to guide exploration and prospecting effectively, the authors made a constraint on the age of molybdenum mineralization on the basis of the geological characteristics and the genesis. δ34S values of the sulfur isotopic range from 2.4‰ to 6.3‰, suggesting that sulfur probably came from magmatic fluid. The authors thus believe that they are products of the same magma-structure-fluid activity. The Mo deposits of Laojunshan area were formed at the same time as Donggou, Yuchiling, Tangjiaping and Jinzhai Mo deposits, and hence should be the response to Late Mesozoic large-scale regional lithospheric extension.