Objective    To investigate the delay phenomenon in a mouse’s ear-flap mode.  Methods  30 male mice were equally divided into the delay group, non-delay group, and below-the-division group. In the delay group, an incision was first made in the middle angiosome right above the division. One week later, the tail-oriented angiosome was severed. In the non-delay group, the ear flap was created by severance of the middle and tail-oriented angiosomes at the level right above the division of the middle angiosome. In the below-the-division group, the ear flap was created by severance of the middle and tail angiosomes at the level right below the division of the middle angiosome. After the creation of the ear flap，The necrotic rate of the ear flaps in the three groups at various time points was calculated; the number and diameter change of the choke vessels that underwent remarkable dilation were recorded and measured.  Results    After the creation, the final necrotic rate of flaps in the delay group, non-delay group, below-the-division group was (7.7±4.8)%, (31.0±12.4)% and (15.4±7.4)%, respectively. There was significant difference among the necrotic rate in the three groups (P=0.003). In the delay group, each ear flap has an average of 8.8±2.0 choke vessels that underwent remarkable morphological changes in each ear, whereas in the non-delay group there were an average of 6.5±1.2 choke vessels in each ear, being significantly less than that in delay group（t=3.083，P=0.006）. The magnitude of the diameter dilation of choke veins in the delay group was remarkably larger than that in the non-delay group. The average intravascular resistance in the delay group was remarkably smaller than that in the delay group.  Conclusion  The delay surgery augments the survival of large-sized flap through enhancement of dilation of choke vessels. The type and handling approach to the middle angiosome might have significant impact on the survival of the flap.