1. People's Republic of China, 2,285,000The People's Liberation Army is the military arm of the People's Republic of China.
It is the largest army in the world.
Military service is compulsory for Chinese men upon reaching the age of 18 years old, but drafting has never been enforced because of the huge number of volunteers.
China has more than a billion people to protect, so having such a large army maybe a necessity.
Its constant skirmishes with its neighbors due to conflicting territorial claims have given the country additional reason to maintain such a strong force.