<p>This paper establishes a geometric model of easy-off Toroidal Enveloping Conical (TEC) worm drive that incorporates errors, and based on this, investigates the influence of mismatched parameters on the tooth contact performance and the sensitivity to errors of this type of worm pair. The study introduces an Adaptive Extremum Search (AES) method to efficiently solve complex nonlinear tooth contact equations, facilitating the accurate determination of instantaneous contact points. Additionally, a mismatch design scheme for this worm pair is proposed, focusing on minimizing the number of mismatched parameters. Numerical examples illustrate the impact of varying mismatched design parameters on tooth contact characteristics. The findings reveal that the shaft angle error exerts the most significant impact on the tooth contact characteristics of the ease-off worm gear. The results also demonstrate that a well-designed mismatched worm pair exhibits strong adaptability to errors. However, it is important to note that excessively small values for the mismatch modification parameters can reduce this adaptability.</p>