Laser welding is an alternative technology for biological tissue reconstruction. The laser weld is small, liquid-tight and does not cause mechanical stress. However, thermal necrosis of the joined living tissue occurs during suture formation, and the depth of suture formation may be much less than required. This paper proposes the use of laser radiation with dynamically varying focusing parameters to reduce the area of thermal necrosis of the attached living biological tissue and increase the depth of suture formation. The influence of laser focusing parameters was evaluated by simulation. Absorption by biological tissue and braze was calculated according to the Beer-Lambert law. The degree of protein conversion in biological tissue and solder was determined using chemical kinetic methods and the Arrhenius equation. Heat transfer was calculated using the thermal conductivity equation.