The flag collection is comprised of over 10000 items, thus becoming the most important of its king in Romania and one of the oldest collections of the National Military Museum. The science which deals with such pieces is called vexillology.

The collection can be divided into Romanian military colours, standards and pennants and foreign colours and pennants. Among the Romanian ones, we can find all the colours and standards belonging to the Romanian military from 1834 up until today, flags belonging to various military type organisations, Royal pennants, banners, poles, flags used at the coronation of King Ferdinand and Queen Maria in Alba Iulia in 1922, as well as several reconstructions of all types and ages.

Forming up the collection was done with the aid of several institutions, some of which no longer exist today, such as: The Army Arsenal, The Royal Palace, The Central Equipment Depository, The Military Navy Headquarters, branch of service inspectorates, the Military Academy and other various other structures, such as the units themselves.

Amidst the most valuable pieces within the collection we can mention the colours which belonged to Prince Constantin Ipsilanti, dating since the beginning of the 19^th century, the first military colours given by Prince Mihai Sturdza in Moldavia and Prince Grigore Dimitrie Ghica in Wallachia, in 1834, or the ones handed by Prince Barbu Ştirbei, Prince Grigore Alexandru Ghica, Prince Alexandru Ioan I, King Carol I, King Ferdinand I, King Carol II, King Mihai I, or even some foreign flags, Ottoman or Austro-Hungarian from the 19^th and 20^th centuries.