A product selection system for a vending machine is provided which is immune to human misbehavior or uncertainty. The system includes a main controller and a plurality of product selection panels connected to the main controller. Each product selection panel includes a plurality of keys, each of which is associated with a type of product stored in the vending machine. When a product selection panel detects a first key-down event, the main controller broadcasts a suspending command to the product selection panels so each product selection panel suspends the detection of any further key-down event in response to receiving the suspending command, until after a product-dispensing routine has been completed or the expiry of a predetermined period of time. A product selection method for a vending machine is also provided.