Abstract: The self-developed optical and magnetic stress device based on plant leaves ultra-weak luminescence was used to study the effect of different magnetic fields on the spontaneous luminescence of jonquil flowers’ leaves and the effect of the same magnetic field on the delayed luminescence of leaves of different leaf ages. The experimental data shows that the effect of the magnetic field on the spontaneous luminescence of the jonquil flowers’ leaves has a saturation time. When the magnetic field acting time is longer than the saturation time, the ultra-weak luminous intensity of the leaves no longer increases significantly, and there are some fluctuations. The influence of the magnetic field on the delayed luminescence 1/p factor of leaves of different leaf ages is different. It has a greater influence on younger and elderly leaves, which takes a long time to eliminate the effect of the magnetic field. The effect on adult leaves is small, and the effect of the magnetic field can be basically eliminated after a short period of time.