Abstract: In recent years, neutron-neutron logging has been ugh widespeadly in coalfield exploration. In this paper, the correlation between the basic data of neutron-neutron logging and various data of the rock and coal quality determined in laboratory is analysed. The results of application of neutron-neutron logging data to the calculation of rock porosity, compressive strength, Brinen hardness factor, formation acoustic impedance,rock components and the size of rock grains are introduced in detail.