The invention discloses a device for starting a side slope siphoning drainage 
system and a method of the device. The device comprises a water tank, air 
discharge pipes and a drainage 
pipe, a water outlet of each 
siphon is formed in the sealed water tank, and an inlet of each air 
discharge pipe is connected to the top of the water tank; an inlet of the drainage 
pipe is connected to the bottom of the water tank, the 
vertical distance between the inlet of the drainage pipe and an outlet of the drainage pipe is larger than the height of a 
water column corresponding to the local 
atmospheric pressure, and the 
height difference between the top of the water tank and a hole opening of a drilling hole is larger than the height of the 
water column corresponding to the local 
atmospheric pressure. According to the device, by controlling opening and closing of the draining pipe, negative pressure is produced to start siphoning without the help of other equipment, and the device is simple and reliable; the 
vertical distance between the inlet of each air 
discharge pipe and an outlet of the corresponding air discharge pipe is larger than the height of the 
water column corresponding to the local 
atmospheric pressure, negative pressure is formed in the water tank, water in the air discharge pipes cannot enter the water tank, it is guaranteed that negative pressure in the water tank is not broken,and accordingly the stability of the whole device is improved; multiple siphons can be started simultaneously, and siphoning is started quickly and efficiently.