Worked as a groom, hammerman, assistant blacksmith at the Uryuktinsky stud farm, from 1925 - a blacksmith in the village of Sazanovka, Issyk-Kul District, from 1928 to September 1929 - a member of the trade union committee of the Uryuktinsky stud farm in Karakol, from February 1929 - an instructor in the trade union committee of agricultural workers in the village of Sazanovka, Kirghiz ASSR and an instructor of the district branch of the trade union of agricultural workers in Karakol.

In October 1929, Nikolai Lyashchenko voluntarily joined the Red Army[2] to participate in the defense of the CER from Chinese militarists.

The conflict was soon resolved, and he was sent to study at the Lenin United Central Asian Military School in Tashkent, from which he graduated in 1932.

During his studies, as part of the combined cadet detachments, he repeatedly participated in combat operations against the Basmachi movement in Central Asia.

From May 1937 to October 1938, Major Lyashchenko participated in the Spanish Civil War, was a military advisor to the commanders of the division and corps of the Republican Army.

During the Voronezh-Voroshilovgrad defensive operation on July 17, 1942, he was surrounded for the second time on the Southwestern Front in the Millerovo area, and on August 3, he reached his own with a detachment of fighters.

[3] After an NKVD check in September 1942, he was demoted to deputy commander of the 18th Rifle Division on the Volkhov Front.

From May 29, 1943 until the end of the war, he commanded the 90th Rifle Division as part of the 2nd Shock Army on the Leningrad and 2nd Belorussian Front.

In January 1944, Lyashchenko's division distinguished itself in the Leningrad–Novgorod offensive, during which, with a blow from the Oranienbaum Bridgehead, it broke through the German defenses that had been under construction for two and a half years, closed the encirclement ring around the enemy group and liberated the cities of Ropsha and Gatchina.

[4] In September 1944, the 90th Rifle Division was transferred to the Baltics, where it again distinguished itself in the liberation of the Estonian SSR from the enemy (the Tallinn offensive, during which the division not only broke through the German defenses, but over the next 10 days fought its way through almost 300 kilometers, liberating two cities and about 300 other settlements[5]), in the East Prussian, East Pomeranian, and Berlin Operations.

General Lyashchenko's division liberated the cities of Pärnu, Osterode, Gniew, Starogard, Danzig, and Swinemünde.

In total, during the war, the 90th Rifle Division was mentioned 16 times in the orders of the Supreme Commander-in-Chief, Joseph Stalin.

He was awarded the title of Hero of the Soviet Union by decree of the President of the USSR Mikhail Gorbachev on October 4, 1990 for courage and heroism shown on the fronts of the Great Patriotic War.