The nonlinear response characteristics of stripe projection of structured light systems often lead to stripe gray-level distortion, adversely affecting both phase and measurement precision. To address the nonlinearity within structured light systems and the differential phase error caused by various degrees of defocused stripes, a novel phase gradient-based regional phase error self-correction methodology is introduced. Initially, the phase is segmented into distinct regions by leveraging data modulation of the stripe image and the gradient information of the wrapped phase. A phase error function is then constructed utilizing the wrapped phase across multiple frequencies, and the phase values from each region are subsequently input into this function for iterative correction. Experimental outcomes indicate a 79.07% reduction in phase error after applying this method. In addition, this approach eliminates the need for stripe pre-encoding, directly addresses errors within the unwrapped phase map, and demonstrates impressive resilience to stripe defocus.