There are a variety of queuing modes for ships to enter the ports. Then through a port handling example, compare M/M/1 to M/M/s two kinds of queuing modes. For an instance, there is a port somewhere, with 3 handling servers. The average ratio for the arrival of ships is λ=0.9 per hour, while the average ratio for service is μ=0.5 per hour. The arrival process for ships obeys the Poisson distribution while the time for handling service obeys the negative exponential distribution. After entering the port, the ships will join the queue to wait for accepting the handling service.