The invention discloses an early warning system for collision in a dead zone. The early warning system comprises a plurality of intelligent handheld mobile devices and a cloud computing platform, wherein the intelligent handheld mobile devices are used for acquiring the speed information, direction information and position information of a user; the cloud computing platform is used for receiving the speed information, direction information and position information acquired by the intelligent handheld mobile devices; and the cloud computing platform is used for computing the collision possibility and sending collision early warning information to the intelligent handheld mobile devices so as to control the intelligent handheld mobile devices to give an alarm. The invention also provides an early warning method for collision in the dead zone. According to the invention, the internet of vehicles, the cloud computing technique and the handheld mobile devices are connected with each other, so that the information interaction capacities of road traffic participators can be promoted; and a cloud computing center is adopted for macro-controlling the road traffic participators, so that the safety and efficiency of the road traffic can be greatly increased.