Micro-nanofiber with crimped structure can be promising in advanced functional application, but its preparation method is still challenged by complex processing, uncontrollable structure and elusive formation mechanism. Herein, a novel continuous self-crimped micro-nanofiber forming method is developed by one-step electrospinning. Through morphological observation, crystal characterization, electrical-performance measurement, mathematical simulation and mechanical analysis, it is shown that the trigger of crimp of polystyrene (PS) electrospinning fiber deposited on wool substrate is the comprehensive differences in diameter size, dielectric constant and electrical conductivity between them and the gap width between substrate fibers. Additionally, the degree of crimp can be adjusted by combining position and form. The theoretical model of multiple forces is established to explain the forming mechanism of crimp, which is further validated by experimental results. Conclusively, this work offers a facile means to inspire crimping of various specific fibers, which can endow them with functional application potentials in wide field.