The invention discloses a method for preparing phosphaalkene by utilizing electrochemistry. The method comprises the following steps: firstly, assembling an electrolytic cell by using an inert electrode as a positive electrode and phosphorus as a negative electrode, wherein in the electrolytic cell, the electrolyte solution is one or several of an aqueous electrolyte solution, an organic electrolyte solution and an ionic liquid electrolyte solution containing the electrolyte; applying direct current or alternating current voltage between the two electrodes of the electrolytic cell and stripping the phosphorus into phosphaalkene under a function of a direct current electric field or an alternating current electric field; and performing filtration treatment to obtain a stripped product, washing the stripped product for a plurality of times by using an organic solvent, centrifugally separating and drying to obtain the required phosphaalkene. According to the method, a phosphaalkene material with good quality, high yield and low cost can be conveniently, quickly and securely produced in an environment-friendly form, and can be applied to multiple fields of secondary ion batteries, supercapacitors, solar batteries, fuel batteries, electro-catalysis, electronic elements, bioanalysis, biological sensors and the like.