He graduated in Law (Master of Laws) from Saint Kliment Ohridski University of Sofia.
Between 2006 and 2008, he was the Bulgarian ambassador to Kazakhstan. In 1986, Filchev earned a doctorate in law. In 1973 he was appointed judge at Varna District Court.
In 1977 he joined the Institute for Legal Studies at The Bulgarian Academy of Sciences as a research associate.
He lectured at the Law Faculty of Sofia University while serving as a judge in Sofia. In 1999 he became Associate Professor of criminal law.
In 1991 the Grand National Assembly elected Mr. Filchev judge at the Supreme Court of Cassation of the Republic of Bulgaria (the Criminal Collage).
Between 1997 and 1999 he served as Deputy Minister of Justice.
He was the Prosecutor General of the Republic of Bulgaria from 1999 to 2006. In 2005 he was conferred the title Professor of criminal law. Between 2006 and 2008, he was the Bulgarian ambassador to Kazakhstan.
Since 1996 he has been Head of the Chair of Criminal law Studies at the Law Faculty of the University of National and World Economy in Sofia, Bulgaria.
Nikola Filchev has specialized in criminal law in Russia and Germany. He has participated in a number of international fora.
He is the author of numerous publications (monographs, studies, articles, etc) in Bulgarian, Russian, English and German on the traching of crime (corpus delicti, culpa, method of committing a crime) and penal lawmaking (public danger, criminalization of acts, differentiation of criminal liability).