A new kind of n-γ combined scintillation detector with n-γamplitude discrimination has been developed. Such a detector is able to detect n andγ rays simultaneously
and give out neutron and gamma signals with different amplitudes. A special device made of 6Li glass as sensitive materials is used as the scintillator. Based on this new developed detector the FT631 Type Combined Moisture/Density Gauge has been designed and produced. The principle and main features of the new detector are described.