The Preliminary Examination of Union Public Service Commission for Civil Services Examination is also popularly called CSAT or Civil Services Aptitude Test.

Scheme of Civil Services Examination . UPSC Preliminary Services Examination 2015 will be on 23rd August 2015 and the last date for receipt of application is 12th June 2015.

The Civil Services Examination consists of two successive stages -
Civil Services Preliminary Examination (Objective type) for the selection of candidates for the Main Examination.

Civil Services Main Examination (Written and Interview) for the selection of candidates for the various Services and post.

Pattern:-
The Preliminary Examination consists of two papers of Objective type (multiple choice questions) each of 200 marks and carries a total of 400 marks.

Scheme of Preliminary Examination
This examination is meant to serve as a screening test only. Only those candidates who are declared by the Commission to have qualified in the Preliminary Examination in the year are eligible for writing the Main Examination of that year.

This is the syllabus of the UPSC prelims exam of 2014.
Syllabus of Paper I
Current events of national and international importance.
History of India and Indian National Movement.
Indian and World Geography - Physical, Social, Economic geography of India and the World.
Indian Polity and Governance-Constitution, Political System, Panchayati Raj, Public Policy, Rights Issues, etc.
Economic and Social Development – Sustainable Development, Poverty, Inclusion, Demographics, Social Sector Initiatives, etc.
General issues on Environmental ecology, Bio-diversity and Climate Change - that do not require subject specialization
General Science

Syllabus for Paper II
Comprehension
Interpersonal skills including communication skills;
Logical reasoning and analytical ability
Decision making and problem solving
General mental ability
Basic numeracy (numbers and their relations, orders of magnitude, etc.) (Class X level), Data interpretation (charts, graphs, tables, data sufficiency etc. - Class X level)
English Language Comprehension skills (Class X level).








for more details here i am giving link of Civil Services question paper
civilserviceindia.com/subject/Prelim%202013%20Paper%201%20English.pdf