The flood protection methods can affect the erosion process of dam-breaking which determines the volume of failure and dam final profile. This article focuses on the experimental models with different protection methods for dam-breaking flood by overtopping. The experiments were conducted in a rectangular tank with an erodible barrier dam made from cohesive sand, including five flood protection methods: diversion trench at the side wall, diversion trench in the middle, wire box, cement protection and geotextile waterproof, to observe and investigate erosion processes. The different water heads between reservoir and downstream of dam over time changing contribute to various inner destructive mechanisms and erosion processes in three directions (vertical, horizontal and backward), which resulted in different erosion volumes. The initial dam-breaking erosion process of barrier dam is related with evacuation of people in downstream area and the final erosion volume is bound up with coverage area of flood as well as the extent of damage. Therefore, we concentrate on the analysis of the initial developmental process and the total erosion value. The results show that the wire box, cement protection and geotextile waterproof can effectively retard the growing larger volume of flood and the diversion trench in the middle can cause the largest erosion volume of dam body. And the erosion processes are determined by the interaction of erosion abilities in three directions. Also, the estimates are presented of the retrogressive erosion velocity, transverse broadening velocity, vertical incision velocity.