The ever-growing demands for energy supply have put great stress on environment protections. Photo-electrochemistry (PEC) is a repaid developing technique which can directly transform solar energy into chemical compounds and have been regarded as a promising strategy to solve the energy and environmental problems. However, the biggest restriction is the fast recombination of photo-generated charge carriers which greatly limits the PEC efficiency. In recent years, introducing external-field into PEC system have been proved to be a powerful method to enhance the PEC performance and attracted more and more attentions. In this review, we summarized the remarkable progresses in external-field enhanced PEC reactions including mechanical stress field, thermal field, electrical field, magnetic field and muti-field coupling. The enhancing principles of different external-fields have also been systemically discussed. Furthermore, the challenges and outlook of the external-field enhanced PEC reactions are presented.