The invention relates to a plant seed treatment method and in particular relates to a method for breaking the dormancy of iris barbata hybrid seeds. The method comprises the following steps: peeling off pericarps and naturally drying; soaking the seeds at a room temperature with clean water for 48 hours; soaking the seeds with a 300mmp-1000ppm 6-BA solution for 12-36 hours; and taking out the seeds and sowing. After the seeds treated by the method are sowed, the seeds can germinate after 46-60 days, and the germination rate can reach 75%; the dormancy of the iris barbata hybrid seeds is effectively relieved, and the time that the seeds germinate in March to April in the next year after being sowed in sand under conventional conditions is brought forward to October of the current year and is brought forward for about 6 months; and the germination rate reaches 75%. The breeding progress of iris barbata is accelerated.