In comparison with the traditional suturing, laser biological tissue welding has the following advantages: shorter operation time, faster wound healing, less tissue damage, and no thread removal. To improve the strength and quality of laser soldering of biological tissues, increase the laser absorptivity in the direction of full-thickness, and explore the effects of dyes on the strength and thermal damage of laser soldering of biological tissues, we use the bovine serum albumin solution as the matrix, chitosan as the stabilizer, and indocyanine green and methylene blue as dyes. We use a Nd∶YAG laser (1064 nm) to weld the skin in vitro with flux and compare the welding effect of flux. Results show that indocyanine green and methylene blue are significant organic chromophores for laser welding. They promote the efficiency of photothermal conversion, improve the welding strength, and reduce thermal damage.