The invention provides a launching method of a pipeline leakage flux inner detector. According to the method, the pipeline leakage flux inner detector is placed on a tray and then placed on a cart through the tray, the pipeline leakage flux inner detector is put into a launching barrel through the tray, and the situation that the pipeline leakage flux inner detector is pulled out together when the tray is pulled out is prevented through a shifting fork push rod; the tray, the cart and the shifting fork push rod are all made of non-magnetic stainless steel; the height and the position can be adjusted through the cart so that the tray can be aligned to the launching barrel; and the shifting fork push rod is used for preventing the pipeline leakage flux inner detector from being pulled out together with the tray. According to the launching method, the launching work of the pipeline leakage flux inner detector can be completed, the launching process is convenient, fast and reliable, and the launching requirement of the pipeline leakage flux inner detector can be met.