Fuzzing and pilling of fabrics, which is one of the factors that affect fabric appearance and wear behaviour, has plagued the people for a long time. With the development of living standard, people have higher and higher requirements on the properties of apparel. Several methods can be used for testing the fuzzing and pilling performance of fabric, and different methods often have different results. Using circular locus method and pilling box method on the four kinds of fabrics at the same time, conduct experimental data processing, compare the advantage and disadvantage of two methods and obtain the principle of selection of them. There are many factors that cause fuzzing and pilling, among which the overall covering factor is a significant one. Through the testing for four different kinds of cotton-wool mixed fabrics, with different warp density and different weft density, establish the relationship between the number of pills and the overall covering factor, and obtain the critical covering factor according to the one factor nonlinear regression equation.