The geneses and ore control are always the important aspects in the study of Pb-Zn deposits. There are different metallotectonic conditions for different genetic type deposits. Statistics show that the interface between silica and calcareous bed is an important ore-control factor for every type of Pb-Zn deposits. This conclusion was reached on the basis of summing up a lot of classic Pb-Zn deposits in China. The interface between silica and calcareous bed is the boundary not only of rock geophysics but also of geochemistry. Three different combined types of interfaces are distinguished. They are interface between intrusion and host rock, volcanic rock and sedimentary rock, different sedimentary rocks.