To obtain transparent polycarbonate (PC) welding samples without adding additional absorbents, 1710 nm and 1910 nm lasers were used to study the transmission welding of PC. The qualities of obtained welding samples were verified by the corresponding weld appearance and the strength of each sample. The experimental results show that the PC welding samples obtained by 1710 nm laser and 1910 nm laser have close strength and desired welding effect. The maximum tensile force of 1334.4 N was obtained by the 1710 nm laser with parameters as follows: 20 W power, 6.5 mm/s welding speed, and -6 mm defocusing amount, and the strength of the welding sample reached 60.9% of the PC substrate.