After high school, Aganov worked at the Moscow Electric Plant, and was the foreman of the assembly team.

In one of his letters, talking about himself, Aganov wrote that his father was an Armenian from Astrakhan, and his mother was a Russian.

He commanded a sapper company, from October 1941 as a senior adjutant (according to modern terminology, corresponds to the position of chief of staff) of a sapper battalion, then from February 1942 as a deputy commander of a motor-engineer battalion, then from April 1942 as an assistant chief of staff of engineering troops of the 54th Army.

After the war, Aganov continued to serve in the headquarters of the engineering troops of the Soviet Army, and was a senior officer in the department.

From November 1955, Aganov served as the head of the engineering troops of the 8th Guards Army in the Group of Soviet Forces in Germany, before he was transferred to teaching work.

In August 1960, he was appointed senior teacher, and in December 1963, as deputy head of the department of the Military Academy of the General Staff.

He made a great contribution to the organization and implementation of measures to eliminate the consequences of the accident at the Chernobyl nuclear power plant.

On 12 December 2017, a postage stamp was issued in Armenia dedicated as "100th anniversary of the birth of Marshal of the Engineering Troops of the USSR Sergey Aganov".