The coiled tubing and plunger lift technologies have been widely used in oil and gas fields around the world. If these two technologies are used in combination, the coiled tubing in horizontal or high-angle wells will undergo bending deformation with the wellbore. Improper plunger will not pass properly in the coiled tubing and may cause blockage or even rigid collision, damage to the coiled tubing. To address the problem of plunger passage in the coiled tubing of high-angle and horizontal wells, the influences of plunger outer diameter, friction coefficient, coiled tubing curvature and inner diameter on plunger passage were considered, and a plunger passage model for coiled tubing in high-angle and horizontal wells was proposed based on orthogonal test. The experimental results show that under the premise of rigid passing, the friction coefficient, coiled tubing curvature and inner diameter are the main factors affecting plunger passage. The new model, modified according to the weight proportion of these three factors, can be used for predicting the entire wellbore and accurately determining the specific blocked section of the plunger. The model was verified through experimental testing, and the verification results were consistent with the model’s predicted results. This model can provide a theoretical basis for plunger selection, plunger design, and optimization in the practical engineering of oil and gas fields.