Abstract: The coiled tubing systems are under complex underground loading. In this paper, the actual depth at which the coiled tubing goes into well is obtained and also the solution about the buckling, the lock-up and the un-lock-up of the coiled tubing. According to the relevant theoretical calculation results, the appropriate geometric parameters of the experimental system are determined. The test bench is designed, the simulation experiments about different specifications and different bending segment length of coiled tubing are carried on. The experimental phenomena about buckling, helical lock-up and top end yielding are analyzed, and the conditions of the helical lock-up are determined. The experimental results are in a good agreement with the theoretical results and may serve as a basis for the analysis of mechanical behavior of coiled tubing in wells.