Hello Abhishek!

Here are the subjects you must prepare for UPSE Civil Service Exams:

Syllabus for Paper 1 (Prelims):

1. Indian History (National movements, independence struggle).
2. Currents affairs (both national and international).
3. Indian politics(Constitution, formation of government, elections, assemblies, levels of government etc).
4. Geography(Physical geography,economic and political of India, world).
5. Environmental studies(climate change and movements, biodiversity etc).
6. Economic development, economy of India, gender issue, demography, poverty, important schemes of govt etc.
7. Aptitude based questions.
8. Logical reasoning and analysis.
9. Comprehension.
10. Basic math.

For Mains:

1. Indian History, culture, heritage.
2. World history, world wars etc.
3. Indian politics, governance, social juistice and international relations.
4. Disaster management, economic development, technology, national security, biodiversity etc.

For more information refer to this article:

https://competition.careers360.com/articles/upsc-ias-syllabus