`Dignaga's Nyaya-dvara-sastra` is the first representative work of his New `Hetuvidya`，in which has collectively reflected `Dignaga's Hetuvidya` ideas in his early days, and it has become the main classical works of Han `Hetuvidya`. For a long period, there are few people make their study on this field for its profoundity.
The author of this paper made entire analysis of the inferential frame of `Dignaga's Hetuvidya`，the basic of its inference，the premise of its Epistemology，the inference form and the validity of inference， etc，which are reflected in `Nyaya-dvara-sastra`. All the analysis above are by means of modern logic and the comparative study method. The paper clarified that the ancient Indian `Hetuvidya` is one of the three logic origins in the world，just like the logic of ancient Greece and China, is developed from the inference by genus, which demonstrated that human thinking has its own generality，and proved that the Oriential civilization has make contribution to the logic development.
There is a tendency of belittling `Dignaga` and praising Dharmakirt among scholars exotic and domestic，because they know little about the rich logic ideals in `Dignaga's Nyaya-dvara-sastra`. Actually，it is `Dignaga` who first made `Hetuvidya` as a independent logic type，(which has been shown exactly in `Nyaya-dvara-sastra`)，while Dharmakirt's contribution was mainly consisted in the aspect of Epistemology.
The author also has the idea that `Nyaya-dvara-sastra` is not only the direct origin of Han `Hetuvidya`，but also has internal logic link with tibetan `Hetuvidya`. That is an important subject of modern `Hetuvidya`，which should be made further study by our all.
