Table of Content: Chapter 1 Introduction 1.1 Introduction 1.2 Factors affecting the magnetic flux leakage testing 1.3 Researches on quantitative inversion of magnetic flux leakage defect Chapter 2 Detection signal processing 2.1 Data acquisition and storage 2.2 Data compression and de-noisie Chapter 3 Quantitative inversion of magnetic flux leakage defect 3.1 Introduction 3.2 Defect quantification based on statistical methods 3.3 Neural network quantification methods based on radial basis function 3.4 Three-dimensional finite element neural network quantification method Chapter 4 Inversion of magnetic flux leakage deficiencies data 4.1 Characteristics of three-dimensional magnetic flux leakage signal 4.2 Random search iterative inversion 4.3 Neural network iterative inversion 4.4 Progressive successive approximation inversion 4.5 Sampling effect on inversion accuracy Chapter 5 3-demensional imaging in magnetic flux leakage testing 5.1 Characteristics of three-dimensional magnetic flux leakage signals 5.2 Quantification for complete signals 5.3 Quantification for incomplete signals Reference