Abstract: Effects of anisotropy on the solidification cracking susceptibility in the molten pool of an Al-Cu alloy are investigated using phase field modeling. The results show that the tip of dendrites becomes stable, side-branches and bridges are difficult to form, and the longer liquid channel is easily formed between dendrites with the increase of anisotropic strength. In the case of large anisotropic strength, welding tensile stresses are difficult to transfer and release through bridging, and the metal melt is also difficult to supply the tensile position through the long liquid channel, so it is easy to form cracks. Based on the simulation results, the solidification cracking susceptibility index |dT/d(f_s)^1/2| is calculated. It is found that the index is higher when the anisotropic strength is larger. In conclusion, the solidification crack sensitivity is higher when the anisotropy strength is larger.