Shape memory alloy has been recently used for tissue fixation in minimal access surgery (MAS). It offers an alternative to conventional thread-based suturing of human tissue, with the advantage that its deployment is faster and requires fewer surgical skills. To minimize the damage to surrounding tissue, thermal analysis of tissue-fixator interactions has been done to optimize the heating method, and to predict the heating effect and affected range. The finite-difference method has been used to solve the one-dimensional transient heat transfer problem, with fixator-tissue conduction boundary condition, and the finite-element method was used to build a three-dimensional model for the design optimization. The predicted temperature responses of tissue are considered within a safety range. Tissue temperature drops quickly after heating, and the affected tissue is limited to a layer 1 mm thick next to the fixator. Further in vivo animal studies on the use of the shape memory alloy fixator are ongoing for future applications of tissue suturing in MAS.