The present invention provides an adjustable dorsal splint for resolving the shortcomings of a typical fixation splint. The invention includes a fixation splint, which contains a splint body, a first retaining portion, and a second retaining portion. A curvature adjustment portion is placed at a preset location of the splint body of the fixation splint, so as to adjust the splint body into predefined bending angle. As the fixation splint is provided with a curvature adjustment portion, it is possible to flexibly adjust the bending angle of the fixation splint to mate with the foot of the patient, thereby maintaining the position of the feet with better efficiency.