The invention discloses an electrochemical preparation method of a uniform and compact cuprous iodide semiconductor film, which comprises the following steps: 1) washing ITO conductive glass or silicon wafers with acetone 2 to 3 times, cleaning the ITO conductive glass or the silicon wafers in an ultrasonic cleaning machine with deionized water, then activating the ITO conductive glass or the silicon wafers in 10% of nitric acid solution, and finally washing with deionized water repeatedly; 2) mixing 0.002-2mol/L of Cu (NO3) 2, 0.002-2mol/L of KI, 3.4 x 10<-6>-1.7 x 10<-3>mol/L of K30 polyvinylpyrrolidone, and adjusting the pH value to 1 to 5 with 2mol/L of HNO3 or 0.1mol/L of NaOH solution to obtain electrolyte; and 3) taking the ITO conductive glass or the silicon wafers as a working electrode, taking a platinum sheet electrode as a counter electrode, and taking a saturated calomel electrode as a reference electrode to obtain the compact cuprous iodide semiconductor film by eletrodeposition, wherein the eletrodeposition voltage of the relative saturated calomel electrode is 0.1-0.4V, the eletrodeposition time is 1-30 minutes, and the electrodeposition temperature is 25-80 DEG C.The invention has the advantages of simple equipment, low cost, low reaction condition requirements and the like.