The condition of the stagnation of the snow due to a bend in a channel, which is the main reason for stagnation in a snow drain channel, is experimentally observed and classified by three parameters ; speed, density and size of the snow mass. The criteria of the blocking is developed by using the relationship between the kinetic energy and the destruction of snow mass. Efficiency of snow removal operation by the snow drain channel is shown by Qw/Qs=4.0-5.0, Qw ; water discharge and Qs ; snow discharge.