It depends on who you see writing electrodynamics. Our school uses Electrodynamics written by Guo and Electrodynamics edited by Ye Bangjiao, which are commonly used in China. Recommended bibliography 1, Landau Volume II, Field Theory, 1 ~ 9 chapters (highly recommended); 2. Jackson's Introduction to Electrodynamics. ; Math recommendation: high numbers and linear algebra are not recommended, both are ok! Methods of Mathematical Physics Liang's Methods of Mathematical Physics (Chapters 1 to 10) and Courand Hilbert's Methods of Mathematical Physics (Volume 1) (Use with caution! )

First, domestic teaching materials

Before studying electrodynamics in China, we mainly need to look at 1 and electrostatic field of electromagnetism, understand Gauss's law and skillfully deduce relevant models. 2. Static magnetic field, knowing Biot-Savart law and skillfully deducing it; 3. Ampere loop law of static magnetic field and be able to skillfully deduce related models; 4. Faraday's law of electromagnetic induction, and be familiar with the derivation of related models; 5. Polarized charge theory and its dielectric function: 6. Clever derivation of magnetized current and its related model; 7. Maxwell equations and their derivation (especially the introduction of displacement current). But it doesn't mean that electromagnetism is so much. There are Mesner effect, BCS phenomenological theory and so on.

You need to learn the contents of mathematical and physical methods and vector analysis, including but not limited to 1, vector analysis; 2. Theory of complex variable function; 3. Integral transform (Laplace transform and Fourier transform); 4. Partial differential equation (equation establishment and variable separation method); 5. Special function theory (Legendre function, Bessel function, Riemannian zeta function, etc. ); 6. Linear algebra (including linear transformation, quadratic form and double line form).

Second, foreign textbooks

Because foreign electrodynamics is field theory, you don't need to know anything about electromagnetism. But you must first learn 1, analytical mechanics (including variational method to derive regular equations, Hamilton theory, Hamilton-Jacobian equation); 2. Special relativity (including relativistic space-time view and relativistic mechanics).

Mathematics must know 1, basic variational method; 2. Calculus and its external differential form; 3. Basic tensor analysis (in the form of Einstein's summation convention); 4. Complex variable function; 5. Integral transformation; 6. Partial differential equations; 7. Special functions.

These are my thoughts.