The invention relates to a preparation method of 
transition metal phosphide Co2P, which includes the following steps that: (1) 
cobalt salt and 
hypophosphite as mixing precursors are dissolved in deionized water, and are stirred until the 
cobalt salt and the 
hypophosphite are completely dissolved; (2) the produced precursor solution is dried; (3) the dried precursor 
powder is loaded into a 
tube furnace, and is calcined under the 
argon atmosphere; (4) the precursor 
powder is cooled to the 
room temperature, the produced product is washed by deionized water and then dried under vacuum, and thereby the 
transition metal phosphide Co2P is produced. The invention has the following advantages that: the sources of the main materials needed by preparation are rich, the prices are low, and therefore the cost is low; the technique is simple, steps, such as high temperature and 
high pressure and temperature 
programming, are not needed, consequently, the preparation flow is simplified, and 
energy consumption is reduced; in the process of preparation, the environment cannot be polluted, and therefore the invention is suitable for 
mass production; and when being used for simulating the 
nickel-
metal hydride battery, the prepared product can show good electrochemical invertibility.