Nonuniform lateral temperature distribution causes the thermal lens effect on the far-field slow-axis divergence angle. To alleviate this effect and improve the slow-axis beam quality, we incorporated a method of adiabatic package by implanting an air gap between the chip and the transition heat sink to reduce the conduction heat dissipation on both sides. Herein, the finite element analysis software ANSYS 18.0 was used to analyze the temperature distribution of chips with the edge adiabatic package. The results show that a chip with contact width 200 μm can reduce the slow-axis divergence angle by approximately 28%, from 11.5° to 8.2°, when the working current is 1.6 A. Likewise, it can reduce the beam parameter product and the beam quality factor by 28% and 24%, respectively. The increase in thermal resistance is 6%. Finally, the implementation of edge adiabatic package has little effect on the lasing wavelength, threshold current, and electro-optical conversion efficiency of the device.