Rural urban population flow Farmers --> Non-agricultural wage earners Rural area --> City

1. Push factor

1.1. increased agricultural productivity --> labour surplus

1.2. difficult lives of farmers

2. Pull factor

2.1. Disparity between rural areas and cities

2.1.1. 1. Living standard

2.1.2. 2. Way of living

2.2. increased job opportunities

2.2.1. increased labour demand

2.2.1.1. enhanced economic development in cities

2.2.1.1.1. reform and opening up policies

3. Rural urban migration

3.1. through national policies

3.2. an official way

4. migrant workers wave

4.1. illegal

4.1.1. caused by slow reform in hukou system

4.2. impacts

4.2.1. deprivation of human rights

4.2.1.1. exploitation by employers

4.2.1.1.1. poor working environment

4.2.1.1.2. wage problem

4.2.1.2. being discriminated against

4.2.2. not covered by social welfare network

4.2.2.1. medical service

4.2.2.2. housing

4.2.2.3. education of offsprings