Magnetic field measurement by electromagnetic induction is a very important problem in electromagnetics． An important method to generate uniform magnetic field is provided by Helmholtz coil． However，the coil is characterized by producing a uniform magnetic field only over a small area near the midpoint of its common axis．A new type of double cone uniform magnetic field generator is designed based on the traditional double circle Helmholtz coil to make the uniform magnetic field more accurate． Finally，the experimental results are compared with the numerical simulation results，and the experimental results are basically consistent with the theoretical ones．Through the improvement of Helmholtz coil，the knowledge is not only helped to better understand and mastered by students，but also is exercised students’hands-on ability and improves students’innovation ability by students． The teaching mode combining new experimental technology and electromagnetic theory has been applied in practical teaching，which makes the abstract physical concepts and formulas become more concrete and visualized，and has also received good teaching effects．