The Nahdlatul Ulama (NU) is quite well known as a religious community organization that maintains the tradition of fiqh with civilization. Because since its inception it has made the ASWAJA ideology the basis of theology, adhering to one of the four schools; Hanafi, Maliki, Shafi'i, and Hambali as guidelines in the practice of Islamic law. The tradition of this diversity often gets criticism and even blasphemy from various parties regarding its validity to live a religious life. Because NU is considered to not have a strong methodology thinking ground, especially in the field of Islamic law. This study examines the epistemology of the NU's kemadzhaban fiq both regarding the meaning of NU about fiqh bermadhab and the methodology of fiqh base...