How did Qin Shihuang rule all the people?

QinShihuang applied strict laws and violence to the people so that the people in the Qin's Dynasty followed the laws and 

order by Qin Shi Huang.

Legalism

In Chinese history, legalism was one of the main philosophic currents during the Warring States Period although the term itself was invented in the han dynasty and  it doesn't refer to an organized ‘school’ of thougt. Legalism was a utilitarian political  philosophy that did not address higher questions like the nature and purpose of life . The school’s most famous proponent and contriputor Han Fei Zi believed 

that a ruler should use the following three tools to govern his subjects . 

Who was Qin Shi Huang

Qin Shi Huang, 

who had a personal name        called Ying Zheng, was the king of the Chinese state from 246 BC to 221 BC during the Warring states Period. He became the first emperor of a unified china in 221 BC. He ruled till his death in 210     BC at the age of 49 .

Unitary System

 A unitary system is a form of government in which authority is concentrated in the central government. Local governments, such as those of regions or cities, are under the control of the central government.This distinguishes a unitary system from the government of a federal state, in which the federation's constituent units themselves have at least some attributes of a sovereign state in their own right that the federal government must respect, and from confederations, in which sovereign states delegate certain powers to a supranational organization.                          

Qin Shihuang's Personalities.

Qin Shi huang was both a brutal tyrant and a great 

leader. He's also responsible for his doings.

He did things that his people were happy and satisfied about . He also protected his people . 

What did he do as a leader of China?

He enforced a single script, making the whole country use the same writing system, currency, measurements, , he also built the Great Wall Of China.  He made his people feel more unified together. Lastly, he cancelled feudalism so the whole country was under 'unified' rule and also used violence to take control of China.