The M101A1 howitzer consists of a cannon (105mm howitzer M2A2), recoil mechanism (M2 series), and carriage (105mm Howitzer, M2A2). The cannon itself is comprised of the tube assembly, breech ring, and locking ring. The cannon is mounted on the recoil sleigh assembly. The firing mechanism is a continuous pull (self cocking) type activated by pulling a lanyard.

The cannon is single-loaded, air-cooled and uses semi-fixed ammunition. The howitzer fires a 105mm (4.2-inch diameter) projectile which can be adjusted for distance and target. The M101 can be used for direct or indirect fire.

The carriage is of the single axle and split trail type. The trails are divided at emplacement, but are drawn together and locked during travel. A drawbar is provided for securing to a prime mover. The carriage consists of an equilibrator, shield, elevating mechanism, cradle, gear, elevating arcs, traversing mechanism, top carriage, wheels, and trails.

The recoil mechanism is a constant hydropneumatic type shock absorber that decreases the energy of the recoil gradually and so avoids violent movement of the cannon or carriage. It is installed in the cradle of the carriage.