"Mathematical Methods in Physics" introduces the mathematical knowledge and the corresponding mathematical foundation needed for physical science research, including 10 chapter, which are the application of variational method, Hilbert space, second-order linear ordinary differential equation, Bessel function, Dirac δ function, Green's function, norm, integral equation, application of number theory in physical inverse problem and basic equation in arbitrary dimensional space. The content of Mathematical Methods in Physics is connected with the mathematical methods that have been learned in the undergraduate stage, reflecting the brand-new scientific research results as much as possible. The explanation of concepts in physics and the derivation of formulas in mathematical methods are detailed and comprehensive, and the content is clearly expressed, which is convenient for readers to learn. A lot of exercises at the end of each chapter help readers to consolidate and expand what they have learned in the text.