This book systematically describes the basic principles, solution processes, commonly used software and example applications of groundwater numerical simulation methods. The book is divided into seven chapters. The first chapter mainly introduces the concepts and characteristics of groundwater numerical simulation methods; the second chapter mainly explains the basic principles and solution process of the finite difference method; the third chapter focuses on the basic principles and solution process of the finite element method; the fourth chapter mainly introduces the numerical method of inversely determining model parameters; the fifth chapter Chapter 6 mainly explains the uncertainty in groundwater numerical simulation and its processing method; Chapter 6 mainly introduces the commonly used software GMS for groundwater numerical simulation and its use; Chapter 7 uses the case study of seawater intrusion to demonstrate the general process of groundwater numerical simulation, and achieves the purpose of applying what is learned through practical exercises. This book can be used as an undergraduate textbook in hydrology and water resources engineering, groundwater science and engineering, water conservancy engineering, environmental engineering and other majors, and can also be used as a reference for hydrogeological researchers and engineering technicians.