The Variation of the mechanical properties of coiled tubing with increasing of the bending cycles was studied based on the fatigue bending cycle machine. The results show that the tensile strength had no significance changes during cycle fatigue. The yield strength and the force value was significantly decreased after 300 cycles, and the corresponding decreased magnitude linearly increased with the increasing of bending cycles. The changing tendency of strain hardening exponent on compression surface is different from the one on extruded surface. When the cycles increase from 100 to 600, the exponent on compression surface shows increases firstly, and decreases afterwards, However, the one on extruded surface shows decreases firstly, and increases afterwards. The yield strengths of the compression surface and extruded surface show the same changing tendency as strain hardening exponent.