This book is dedicated to phase shift analysis in nuclear reaction. In the introduction chapters the main notions (nuclear reaction, Schrodinger Equation, nuclear potential, nuclear well, penetrabilities, widths, resonance, virtual states, phase shift, S-matrix formalism and others) are well define in a conprehensive, concise way with many concrete examples. The book addresses to students, young and senior researchers in nuclear physics. The book was written in Romanian and in Russian languages and is based on personal experience of the author during his work at Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH Bucharest-Magurele, Romania, http://www.nipne.ro) and Joint Institute for Nuclear Research (JINR, http://www.jinr.ru) Dubna, Moscow Region, Russian Federation. As I known Prof. Alexandru Florian Nichitiu curently is living in Toronto, Ontario, Canada and teaches at Toronto University.